ICMCTF2013 Session CP: Syposium C Poster Session

Thursday, May 2, 2013 5:00 PM in Room Grand Hall

Time Period ThP Sessions | Topic C Sessions | Time Periods | Topics | ICMCTF2013 Schedule

CP1 Electrical and Optical Properties of AZO/Ag Bilayer Prepared by Transfer Printing Method
Myoung-Soo Kim, Da-Hyeok Lee, Young-Hwan Cha, Beom-Hoan O, Seung-Gol Lee, Se-Geun Park (Inha University, Republic of Korea)

Recently, transfer printing has been widely used to form metal electrodes on various plastic substrates. This process can be applied to flexible display or organic solar cell application. Only a few metals such as Au, Ag and Cu have been employed in these applications because these metals have the property of 'glues' and 'releases' with substrate materials. The surface energy difference and cross-linking between metal and organic materials are key factors. Pure metals have better electrical properties but less optical transparency than transparent conducting oxides (TCO) and thus new structures such as TCO/Metal bilayer or TCO/Metal/TCO tri-layer have been studied. In this work, we have demonstrated that a structure of TCO/metal bilayer can be prepared successfully by a transfer printing method. A bilayer of Al-doped ZnO(AZO) and silver films sequentially deposited on poly(dimethyl siloxane) (PDMS) mold by RF magnetron sputtering is transferred onto polyester film(Obducat UV sheet) at 120oC. Anti-sticking layer (METAX fz-610, Kanto kasei) are coated on PDMS mold pattern. The AZO layer thicker than 8 nm cannot be transferred because of film cracking, and Ag layer thinner than 5 nm is not enough for an adhesion layer. I-V characteristics of line patterns of AZO/Ag bilayer lines were measured. It is found that the transferred bilayer line has higher electrical resistance due to poor uniformity of METAX films formed by spin-coating and that optical transmittance of the bilayer is decreased as thickness of AZO layer is increase at the fixed thickness of Ag layer. As AZO becomes thicker surface roughness becomes larger and causes more scattering of the incident light.

CP2 Characterization of Hysteresis Phenomena in Indium Zinc Oxide Thin Film Transistors with Double-channel Layers via Capacitance-voltage Measurement
Won Kim, Sang-Hyuk Lee, Jin-Seok Park (Hanyang University, Republic of Korea)

Lately, zinc oxide (ZnO)-based semiconductors have been investigated as active channels of transparent thin-film transistors (TFTs) for organic light-emitting diodes and transparent displays because of their excellent electrical and optical properties at room temperature. Most of the researches have mainly been focused on improving the device performances of the TFTs. However, the electrical instability such as the threshold voltage shift due to the hysteresis phenomenon in the current-voltage characteristics of oxide-TFTs may need to be considered for practical applications. It is known that the electrical hysteresis may occur through several processes, such as electron injection and trapping within the gate insulator or deep state creation for the explicit case of a metal vacancy or electron trapping within the oxide channel layer. However, the exact mechanism responsible for the hysteresis is not clear yet.

In this study, we have investigated the hysteresis in the oxide-TFT which uses amorphous indium zinc oxide ( IZO) as the active channel. The IZO-based TFTs were fabricated with a bottom-gate structure. The IZO channel layers were deposited on thermally oxidized Si substrates (gate) via RF sputtering. Some of the IZO-TFTs had double channels which were formed by two-step deposition procedures. Here, the 1st-IZO layer was deposited at relatively low oxygen contents in the O2/Ar gas mixture. Then, the 2nd-IZO layer was deposited at the higher oxygen contents without stopping the vacuum. The source/drain electrodes were also deposited with IZO films using the same RF sputtering system under a pure Ar environment. The forward and reverse voltage-sweep transfer characteristics of the fabricated IZO-TFTs were measured. The threshold voltage shift (ΔVth) caused by the hysteresis was increased with the thickness and oxygen content of the IZO layer. The charge trapping mechanism responsible for the ΔVth was examined by constructing the small-signal equivalent circuits for the single- and double-channel structures of IZO-TFTs and also measuring their capacitance-voltage (C-V) characteristics in the frequency range of 1 kHz – 10 MHz. From the C-V measurement, the interface trap density (Dit) and channel trap density (Dch) were estimated in terms of the oxygen contents used for deposition of IZO-channel layers. The results indicate that more metal vacancies and oxide interstitials can be created for the IZO-channel layers with the greater incorporation of oxygen and the larger thickness. It is also noted that the channel trapping is dominant at the higher oxygen contents, but the interfacial trapping becomes a majority trap at the lower oxygen contents.

CP3 Effects of RF Power and Oxygen Gas on the Characteristics of Thin Film Transistors with Co-sputtered Silicon Zinc Oxide Channel Layers
Sang-Hyuk Lee, Won Kim (Hanyang University, Republic of Korea); Hyun-Seok Uhm (Samsung Display, Republic of Korea); Jin-Seok Park (Hanyang University, Republic of Korea)

Zinc oxide (ZnO)-based semiconductors as active channel layers for thin film transistors (TFTs) recently have attracted much attention due to their excellent characteristics such as higher mobility than amorphous silicon, the ability to perform room-temperature deposition, and high transparency. However, most of the successful ZnO-based TFTs incorporate indium (In), e.g. indium zinc oxide (IZO), indium zinc tin oxide (IZTO), and indium gallium zinc oxide (IGZO), which is relatively rare on Earth. This makes those technologies easily subject to a material shortage. Recently, some researchers have reported experimental results which demonstrate new oxide semiconductors free of In, such as aluminum zinc tin oxide (AZTO), magnesium zinc oxide (MZO), and titanium oxide (TiOx), as another alternative channel layers for oxide TFTs. Also, it has been known that the group IV elements (such as Si, Ge, Ti, Zr, Hf) may act as effective donors in the ZnO lattice because they may be substitutionally placed on the Zn sites and then enhance the carrier concentration and conductivity.

In this study, we suggest a novel transparent oxide TFT which has a silicon zinc oxide (SZO) channel layer. The SZO-based TFTs with a bottom-gate structure were fabricated by the following procedures. An n-type Si (100) wafer with a low resistivity (below 0.002 Ωcm) was used as a gate electrode, and a gate insulating layer was formed by thermally oxidizing the Si substrate. Then, the SZO channel layers were deposited via a co-sputtering method using two separated targets of ZnO (99.999 % of purity, 4 inch of diameter) and boron (B)-doped Si (99.999 % of purity, 0.1 Ωcm of resistivity), by varying the applied RF powers and the flow rates of oxygen gas. Finally, aluminum (Al) films were deposited via DC magnetron sputtering, followed by a lift-off process to form the source-drain electrodes. The various methods, such as four-point probe, X-ray diffraction (XRD), UV/visible spectrophotometer, secondary ion-mass spectrometry (SIMS), and x-ray photoelectron spectroscopy (XPS), were used to investigate the effects of the rf power and oxygen gas on the electrical, structural, and optical properties of the deposited SZO films. The output and transfer current-voltage characteristics of the fabricated SZO-TFTs were measured using a semiconductor parameter analyzer (4200-SCS, Keithley). The role of Si incorporation in determining the device characteristics of the SZO-TFTs was extensively examined. In addition, the relationship between the material properties of the SZO films and the device characteristics of the SZO-TFTs was discussed in detail.

CP6 Effect of Thickness on the Structure and Optical Properties of Yttrium-Doped Hafnium Oxide Nanocrystalline Thin Films
Chintalapalle Ramana, Alejandro Ortega, Mohammed Noor-A-Alam, Abhilash Kongu (University of Texas at El Paso, US)

Hafnium oxide (HfO2) is a high temperature refractory material with excellent physical, electronic and chemical properties. The outstanding chemical stability, electrical and mechanical properties, high dielectric constant (high-k), and wide band gap of HfO2 makes it suitable for several industrial applications in the field of electronics, magneto-electronics, structural ceramics, and optoelectronics. HfO2 has been identified as one of the most promising dielectric to replace SiO2 in nano-electronics. Hafnium oxide exhibits various polymorphs; monoclinic, tetragonal, and cubic. Doping a small amount of yttrium stabilizes the HfO2 cubic phase. The high temperature cubic HfO2 phase stabilized by Y-doping has been shown to exhibit increased dielectric constant compared to that in monoclinic phase. In the present work, yttrium-doped hafnium oxide (YDH) films were produced by sputter deposition on quartz and sapphire substrates at 400 °C by varying the deposition time in a wide range. YDH films with a thickness range ~20-1000 nm were produced by sputter-deposition. The grown YDH films were analyzed using X-ray diffraction, scanning electron microscopy (SEM) and optical spectrophotometry to understand the effect of film thickness on the microstructure and optical properties of YDH films. The XRD and SEM results indicate that the phase evolution and grain size were dependent on the film thickness. The cubic phase of YDH is seen for films with a thickness ≥60 nm. An increase in band gap from 5.2 to 5.5 eV is observed with film thickness. A correlation between growth conditions, thicknesses, and optical properties of the YDH is discussed.

CP7 Impact of Mechanical Strain on Hot Carrier Degradation for Partially Depleted Silicon-On-Insulator n-channel Metal-Oxide-Semiconductor-Field-Effect-Transistors
WenHung Lo, Ting-Chang Chang, JyunYu Tsai (National Sun Yat-Sen University, Taiwan, Republic of China)

This work studies impact of mechanical strain on hot carrier (HC) degradation for partially depleted silicon-on-insulator (SOI) n-channel metal-oxide-semiconductor-field-effect-transistors (MOSFETs). In general, conventional floating body (FB) effect can aggravate HC effect for SOI FB-type MOSFETs. For ultra-thin gate oxide, gate-induced-floating-body-effect (GIFBE) becomes a candidate to influence device performance under HC stress. By measurement of body current (I­B), we can examine the body charging behavior and clarify mechanism. Additionally, it can be found that the maximum of IB (IBmax) shows two stage trends under application of VD. While VD<1V, IBmax decreases as VD increases, since GIFBE is diminished by expansion of depletion region. Beyond VD=-1V, IBmax increases with VD due to impact ionization. Therefore, aggravated HC degradation for FB device is attributed to conventional FB effect instead of GIFBE, even for ultra-thin gate oxide low power devices. Furthermore, we study the influence of mechanical strain on HC stress for SOI MOSFETs. It can be seen that performance of grounder body (GB) device with strain shows more significant degradation than that without strain during stress. This is because band gap narrowing enhances impact ionization. However, FB device shows invariant under HC stress before and after strain, since FB effect could make a competition between enhancement of impact ionization rate and electric field of depletion region lowing.

Keywords: Hot Carrier Stress, GIFBE, PD SOI, n-MOSFETs, Strain

Corresponding author’s email: tcchang@mail.phys.nsysu.edu.tw (T. C. Chang)
CP8 Abnormal Threshold Voltage Shift under Hot Carrier Stress in Ti1-xNx/HfO2 p-channel MOSFETs
JyunYu Tsai, Ting-Chang Chang, WenHung Lo (National Sun Yat-Sen University, Taiwan, Republic of China)
This work investigates the channel hot carrier (CHC) effect in HfO2/Ti1-xNx p-channel metal oxide semiconductor field-effect transistors (p-MOSFETs). We found that the degradation of device is dominated by electron trapping since threshold voltage (Vth) shows a positive shift (Vth lowering) with an invariant of sub-threshold swing (S.S), resulting in an instability on device. It can be seen that Vth under saturation region shows insignificant degradation after CHC stress. This is because depletion region due to drain voltage (VD) covers trapping area to screen the influence of electrons. However, Vth under linear region has unusual shift under CHC stress. In general, electron trapping for p-MOSFETs locates at drain side rather than near center of channel, thus trapping behavior does not vary Vth of channel. According to that, electron trapping induced drain-induced barrier lowering (DIBL) is proposed to explain the abnormal behavior of Vth for linear region. Additionally, the influence of different concentration of nitrogen for HfO2/Ti1-xNx p-MOSFETs on CHCS also investigates in this work. Since nitrogen-induced pre-Nit during process degrade channel mobility, the device with more nitrogen shows slighter impact ionization, leading an insignificant charge trapping-induced DIBL behavior.
CP9 Electrical Enhancement of Nitrogen Doped Amorphous In-Ga-Zn-O Thin Film Transistors by Microwave Annealing
Chur-Shyang Fuh, Po-Tsung Liu, SimonM, Sze, Sih-Wei Huang, Mei-Jeng Liu, Chih-Hsiang Chang (National Chiao Tung University, Taiwan, Republic of China)

We investigated on the physical characteristics and electrical performance of nitrogen doped amorphous In-Ga-Zn-O thin film transistor (IGZO:N TFT) without any channel passivation layer. By using microwave annealing technology instead of thermal furnace annealing, the electrical characteristics of a-IGZO:N (N2 = 2sccm) thin film transistor could improve obviously from normally off to a transfer characteristic with a carrier mobility of 4.97 cm2/Vs, threshold voltage of 3.98 V and subthreshold swing of 0.39 V/decade. This TFT performance with microwave annealing of 300s is well competitive with its counterpart with furnace annealing at 450℃ for 1 hr. The a-IGZO:N TFT performance especially in mobility could further improve by increasing the microwave annealing time from 100s to 600s. Besides, we also discussed the nitrogen containment in a-IGZO with different flow rate of nitrogen gas mixed with argon gas during thin film deposition by DC sputtering system. With the nitrogen flow rate increased from 0 to 2sccm, the mobility of device is enhanced significantly from 2.06 to 4.97 cm2/Vs and the threshold voltage is lowered from 8.83 to 3.89 V. The effective carrier concentration in a conductive oxide semiconductor might be increased due to the doping of nitrogen with low electronegativity.

CP10 Chemical Bath Deposited Zn-Cd-S Buffer Layer for Cu(In,Ga)Se2 Solar Cells
YiChen Lin (National Chung Hsing University, Taiwan, Republic of China); ZueChin Chang (National Chin Yi University of Technology, Taiwan, Republic of China); Fuh-Sheng Shieu (National Chung Hsing University, Taiwan, Republic of China)

Fabrication of Zn-Cd-S films by Chemical bath deposited (CBD) has been studied for use as buffer layers in Cu(In,Ga)Se2 (CIGS)-based solar celldevices.The Zn-Cd-S films were grown using zinc sulfate, thiourea , cadmium acetate and ammonia water in the temperature 70℃.The process gives good control of thickness and [Cd]/([Cd]+[Zn]) content of the films.

The prepared films were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and UV–vis spectroscopy.The band gap increased from 2.4 to 3.8eV with increasing [Cd]/([Cd]+[Zn]) from 0 to 1. The Zn-Cd-S buffer layer of efficiency enhance and it was shared better the lattice matched with CIGS.

CP11 Investigation on Amorphous InGaZnO Based Resistive Switching Memory with Low-power, High-speed, High Reliability and Good Flexibility
Yang-Shun Fan, Ching-Hui Hsu, Po-Tsung Liu (National Chiao Tung University, Taiwan, Republic of China)

Recently, nonvolatile memory (NVM) has been widely used in electronic devices. Nowadays, the prevailing NVM is Flash memory. However, it is generally believed that the conventional Flash memory will approach its scaling limit within about a decade. The resistive random access memory (RRAM) is emerging as one of the potential candidates for future memory replacement because of its high storage density, low power consumption as well as simple structure.

The purpose of this work is to develop a reliable a-InGaZnO based resistive switching memory. We investigate the resistive switching characteristics of TiN/Ti/IGZO/Pt structure and TiN/IGZO/Pt structure. The device with TiN/Ti/IGZO/Pt structure exhibits stable bipolar resistive switching. The impact of inserting a Ti interlayer is studied by material analyses. The device shows excellent resistive switching properties. For example, the DC sweep endurance can achieve over 1,000 times; and the pulse induced switching cycles can reach at least 10,000 times. In addition, we demonstrate the possibility of MLC IV operation for the device. By controlling the compliance current, multi-level operation can be achieved. Besides, the pulse induced switching is also performing on the MLC operation by adjusting the pulse amplitude. Furthermore, the impact of different sputtering ambient, the temperature instability, and the conduction mechanisms are also investigated. According to our experiment s, we propose a model to explain the resistive switching phenomenon observed in our devices.

Finally, because the whole fabricating process of the RRAM device is under room temperature, it holds the potential for flexible electronics applications. The TiN/Ti/IGZO/Pt RRAM device is fabricated on flexible stainless steel to test its flexibility and mechanical endurance.

CP12 Effect of Sn-layer Addition to Precursors on Characteristics of Cu2ZnSn(S,Se)4 Thin Film Solar Cell Absorber
Kim Sammi, Kim Woo Kyoung, Oh Misol, Lee Soobin, Jeon Soyoung (Yeungnam University, Republic of Korea)
Kesterite Cu2ZnSn(S,Se)4 (CZTS(e)) compound semiconductor is characterized by direct band gap energy and high absorption coefficient (α ~ 104 cm-1), which are suitable for photovoltaic applications. In addition, rare-earth material such as Ga and In within high-performance Cu(InGa)Se2 solar cell absorber are replaced by Zn and Sn which are naturally abundant and thus relatively inexpensive. Band gap energies of CZTS(e) semiconductors vary in the range of 0.95~1.5 eV, depending on the relative contents of S and Se. Several vacuum and non-vacuum synthesis methods have been explored to form the kesterite compound. CZTS solar cells with 0.66% efficiency using vacuum-based process were first reported in 1997 by Katagiri et al. Recently, IBM reported considerable conversion efficiency of 8.4% for CZTS cells fabricated by thermal evaporation of elemental Cu, Zn, Sn and S in a vacuum system. The record efficiency of 10.1% (AM1.5) achieved for kesterite photovoltaic absorber of CZTS(e) was also reported by IBM, using hydrazine-based solution process. However, their process may be difficult to be commercialized due to toxicity of hydrazine solvent. In our study, 3-step sputter/selenization/sulfurization process was employed. Precursors were prepared on Mo-coated glass substrate by sequential and/or simultaneous sputtering of Cu, Zn and Sn metal targets. Two kinds of precursor structures, Mo/Zn/(Cu+Sn) and Mo/Sn/Zn/(Cu+Sn), were employed to evaluate the effect of addition of Sn layer to Mo/Zn interface. Selenization and sulfurization of precursors were performed using Se vapor and H2S gas in a rapid thermal process system, with the reaction temperatures of 380 °C for selenization and 480-600 °C for sulfurization. The results demonstrated that the insertion of Sn layer into the interface of Mo/Zn mitigated the overall Sn loss and delamination of CZTS(e) films. Further details of sulfurization temperature effect on the resulting CZTS(e) thin films will be discussed.
CP13 Rapid Sulfurization of CuGaIn/Se Precursors
Lee Soobin (Yeungnam University, Republic of Korea); Cho Hyun-il, Son Changgil, Ahn Donggi, Kim Byoungdong (Samsung SDI, Republic of Korea); Kim Woo Kyoung (Yeungnam University, Republic of Korea)

Cu(InGa)Se2 (CIGSe)-based chalcopyrite thin film has been employed as a desirable light absorber for thin film solar cell, recently yielding 20.3% cell efficiency (2010, ZSW). Typically, either the selenization of CuGaIn metal precursor selenization or elemental co-evaporation is used to fabricate CIGSe layers. Especially, selenization using the rapid thermal processing (RTP) of Se-coated CuGaIn precursors followed by sufurization by H2S was successfully scaled up by Avancis company, reporting a conversion efficiency of 13.9% at 65ⅹ165 cm2 module. It is assumed that the partial substitution of Se with S is intended to improve Ga depth uniformity within absorber and increase band gap energy at the surface of absorber layer.

In this contribution, the sulfurization process of CuGaIn/Se precursors by H2S was investigated with a particular emphasis on the phase evolution and compositional depth profile. The CuGaIn metal precursors were prepared by either sequential or simultaneous sputtering of CuGa and element In target, followed by thermal evaporation of Se. The reactive selenization and sulfurization of precursors were carried out in a tube-type rapid thermal process system at the temperatures of 450-570 °C and 570-600 °C, respectively. In-situ phase evolution during sulfurization was observed by high-temperature X-ray diffraction scan. Compositional depth profile was measured by transmission electron microscope and secondary ion mass spectrometer. Morphology during sulfurization was analyzed by scanning electron microscopy of samples obtained by intentional quenching during reactive annealing. It was found that replacing Se of CIGSe structure by S would affect the formation of MoSe2 and Ga incorporation. Also, the degree of S dosing would be affected by the degree of selenization at the first stage, which is controlled by selenization conditions such as the thickness of Se layer, reaction time and temperature.

CP14 Electrical and Optical Properties of Magnesium Doped Delafossite Structure CuCr1-xMgxO2 Reactively co Sputter Deposited Coatings
Pascal Briois, Mohammad Arab Pour Yazdi (IRTES-LERMPS-UTBM, France); Jean-François PIERSON (Institut Jean Lamour, France); Alain Billard (IRTES-LERMPS-UTBM, France)

Transparent conducting oxides (TCOs) are materials with rather high electronic conductivity and low optical absorption of the visible light which can be used in many applications in transparent electronics, e.g. light emitting diodes, photovoltaics, smart windows or flat panel displays.

The p-type TCOs mainly consist in spinel and delafossite materials with AB2O4 and ABO2 stoichiometry, respectively. Very few papers deal with the deposition of delafossite structure coatings which however are of strong importance for the development of new transparent devices which are not feasible with n-type materials alone, e.g. transparent diodes, transistors or heterojunctions.

In this paper, we investigate the feasibility of magnesium doped p-type delafossite structure CuCr1-xMgxO2 coatings by co sputtering of metallic targets in argon-oxygen reactive gas mixtures.

After a short description of the experimental device were the substrates are positioned on a rotating substrate holder, the coatings are performed in so called compound sputtering mode by fixing the discharge current of the Cr target and by modifying that of the Cu or Ag one. Hence, the chemical, structural, microstructural and morphological features of the coatings are investigated via scanning electronic energy dispersive X-ray spectroscopy, X-ray diffraction and scanning electron microscopy on thick films. Complementary structural data are assessed by Fourier transmission infrared spectroscopy and Raman spectrometry. The optical properties of the films are assessed by optical transmission spectrophotometry and their electrical conductivity is determined by using four point probe method.

Finally, the influence of annealing performed in air at different temperatures is investigated owing to the structural, optical and electrical properties of CuCr1-xMgxO2 coatings.

CP15 High Power Impulse Magnetron Sputtering of Transparent Conducting Oxides
Li-Chun Chang, Ching-Kuang Chang, Szu-Chin Wang (Ming Chi University of Technology, Taiwan, Republic of China)
High power impulse magnetron sputtering (HIPIMS) has been used in order to study the deposition of transparent conducting oxides. We summarize the studies carried out on aluminium-doped zinc oxide - AZO using reactive sputtering. For the deposition of AZO reactive HIPIMS for metallic targets has been used. In this study, a plastics was used as a flexible substrate. A feedback control loop has been implemented in order to stabilize the discharge at any given setpoint on the hysteresis curve. The hysteresis was also found to have a rather untypical form. Reactive HIPIMS was found to be a promising tool for obtaining high quality films of low total thickness.
CP16 Synthesis of Silver Nanowire by Polyol Method for Transparent Conductive Film Application
Jung-Jie Huang (MingDao University, Taiwan, Republic of China); Jian-Yang Lin (National Yunlin University of Science and Technology, Taiwan, Republic of China); Chao-Nan Chen (Asia University); Yu-Lee Hsueh (National Yunlin University of Science and Technology, Taiwan, Republic of China); Ming-Wei Tsai (MingDao University, Taiwan, Republic of China)

In the study, we used the polyol method to synthesize silver nanowire, and the use of silver nitrate (AgNO3) as the precursor for seeds. The experimental results show that the different synthesis temperature, Poly(N-vinylpyrrolidone) (PVP) molecular weight, the concentration of reactants and the addition rate of silver nitrate will affect the growth characteristics of silver nanowires. Field-emission scanning electron microscopy, UV-vis spectrophotometer and x-ray diffractometer have been employed to characterize the silver nanowires. When the synthesis temperature is higher than 180℃, the nucleation rate is too fast. Therefore, the particles are homogeneous nucleation and the formation of silver particles. When increasing the concentration of PVP, the diameter of the silver nanowires will be widened to cause a smaller aspect ratio. This study successfully prepared silver nanowires with a diameter of 120 nm and a length of 20 μm. Finally, the transmittance and sheet resistance were measured by UV-vis spectrophotometer and four-point probe I-V test, respectively. The solution-type silver nanowire thin film shows high transmittance, low sheet resistance and can be used for transparent conductive film application.

CP17 Performance Improvement of Hybrid Solar Cells with Thermally Evaporated Cuprous Oxide as a Hole Transport Layer
Yang-Yen Yu, You-Jhe Wang, Ming-Feng Hsu (Ming Chi University of Technology, Taiwan, Republic of China)
In this study, a polymer solar cell with a thermally evaporated cuprous oxide (Cu2O) as the hole transport layer between the active layer and the top anode was fabricated. The Cu2O thin film can module the Schottky barrier and form an ohmic contact at the organic/metal interface, which make it a great holes transport layer. The device performance obtained from different Cu2O thicknesses and different annealing temperature and time are investigated. The results show that the cell stability increases with Cu2O as the hole transport layer compared to the control cell without Cu2O.
CP18 Nanocomposite Anti Bacterial Sputter Deposited Coatings
Eric Monsifrot (Dephis, France); Frédéric Sanchette (ICT, France); Alain Billard (IRTES-LERMPS-UTBM, France); Frédéric Schuster (CEA, France)

Anti bacterial surfaces are of increasing importance for various applications. Among the coatings able to ensure antibacterial activity, both crystallized titanium dioxide that allows photocatalytic destruction of bacteria under UV irradiation and noble metals such as Cu or Ag introduced into a ceramic matrix are known as suitable alternatives.

Association of titanium dioxide with a noble metal in a nanocomposite coating is an alternative susceptible to allow both effects. Among the technologies able to produce nanocomposite TiO2-Cu(Ag) coatings, reactive co sputtering is known as a powerful technique.

In this paper, after a short description of the industrial vessel used for the deposition of TiO2-Cu(Ag) nanocomposite coatings using plasma emission monitoring, we investigate the effect of emission setpoint of the titanium target and discharge current dissipated on the noble metal target on the structure of as-deposited TiO2-noble metal coating.

Finally, anti bacterial tests are performed using two model bacteria, i.e. escherichia coli and staphylococcus aureus, to give tendancies owing to the nanocomposite structure on the anti bacterial activity.

CP19 Organic Thin-film Transistors with Polymer–nanoparticle Hybrid Dielectrics Layer
Yang-Yen Yu, Yung-Chih Chen (Ming Chi University of Technology, Taiwan, Republic of China)
In this study, a high-performance organic thin-film transistors (OTFTs) with a nanocomposite dielectric and semiconducting layer has been demonstrated. The dielectric and semiconducting layer is prepared from the polyimide/barium titanate (PI/BaTiO3) nanocomposite and pentacene, respectively. It was found that the OTFTs with the PI/BaTiO3 nanocomposite dielectric layer have higher field-induced current than that of conventional devices because the dielectric constant of the gate insulator is increased. In addition, the dielectric constant of PI/BaTiO3 is tunable by controlling the solid content of BaTiO3 in nanocomposite. The results shows the present PI/BaTiO3 has a great potential as the dielectric layer for the preparation of high-performance OTFTs.
CP20 Investigation of Sputtered GAZO Films for CIGS Photovoltaics
Chia-Hua Huang (National Dong Hwa University, Taiwan, Republic of China); Hung-Lung Cheng (Natioanl Dong Hwa University, Taiwan, Republic of China)
With the conversion efficiency of over 20% and the potential of low-cost production, Cu(In,Ga)Se2 (CIGS) solar cells have drawn much attention in recent decades. Aluminum doped zinc oxide (AZO) films have been extensively used as the window layers for the high-efficiency thin-film CIGS solar cells. Due to the high reactivity of aluminum with oxygen resulting in oxidation of aluminum, the long-term stability of CIGS solar cells with the AZO films as the window layers is deteriorated when the CIGS solar modules are under the environments of high temperature and humidity. In contrast to aluminum, gallium is less reactive and more resistant to oxidation. In order to fulfill the requirements of both performance and stability for the transparent electrodes in the photovoltaic applications, the aluminum and gallium codoped zinc oxide (GAZO) thin films were investigated. Most deposition techniques for the preparation of GAZO films require the elevated substrate temperature during the deposition to achieve the better properties of as-deposited films. However, the deposition temperature for the front contacts must be lower than 200°C, otherwise the junction properties of CIGS solar cells will be ruined. The GAZO films were deposited on the glass substrates by magnetron sputtering technique using a single ceramic target. Deposited at the substrate temperature below 200°C, the electrical and optical properties of GAZO films employed as the window layers for Cu(In,Ga)Se2 (CIGS) solar cells were optimized. The deposition parameters including working pressure and working power were varied to investigate their effects on the microstructral, electrical, and optical properties of GAZO films. The crystalline structure of films was studied using X-ray diffraction (XRD), and the surface morphology and cross-sectional view were observed by field-emission scanning electron microscope (FE-SEM). The carrier concentration, mobility, and resistivity of as-deposited films were measured by a Hall measurement system. The optical transmittance was measured with an UV/VIS spectrophotometer. In addition, the band gap energies of GAZO films were determined from the optical properties. The impacts of sputtering parameters on the structural, electrical, and optical properties of GAZO thin films was thoroughly studied through the detailed characterization of as-deposited films. Under the given deposition conditions, the GAZO films of 400 nm in thickness possessed a low sheet resistance below 10Ω/□ and high optical transmittance of over 85% in the visible region.
CP21 Investigation of Green and Yellow Luminescence from Alpha and Beta Zinc Silicate Thin Films Doped with Manganese
YeonKi Cho, JooHan Kim (Chungbuk National University, Republic of Korea)
The green and yellow luminescence from alpha and beta zinc silicate (Zn2SiO4) thin films doped with manganese were investigated. The Mn-doped Zn2SiO4 films were prepared by radio frequency magnetron sputtering in an argon/oxygen gas mixture. X-ray diffraction (XRD) patterns revealed that the as-prepared Zn2SiO4:Mn films were of amorphous structure. The amorphous Zn2SiO4:Mn films were crystallized by post-deposition annealing in an air atmosphere at temperatures ranging between 800 and 1200 oC for 1 h. It was found that the Zn2SiO4:Mn films annealed at 800 oC possessed a mixture of alpha and beta phases. The obtained photoluminescence (PL) spectrum consisted of two emission bands centered at 525 nm in the green range and 574 nm in the yellow range. The green luminescence originates from the Mn2+ ions in alpha phase of zinc silicate (α-Zn2SiO4), while the yellow luminescence comes from the Mn2+ ions in β-Zn2SiO4. However, the films annealed at and above 900 oC exhibited only the alpha phase and the crystallinity was improved with increasing annealing temperature up to 1200 oC. The PL spectra showed only the green emission band with a peak maximum around 523 nm. The PL emission intensity was enhanced as the annealing temperature was increased, resulting from improved crystallinity of the α-Zn2SiO4:Mn films. The broad PL excitation band was observed ranging from 220 to 300 nm with a maximum at around 243 nm.
CP22 Effect of the Thin Ga2O3 Layer in n+-ZnO/n-Ga2O3/p-Cu2O Heterojunction Solar Cells
Yuki Nishi, Toshihiro Miyata, Tadatsugu Minami (Kanazawa Institute of Technology, Japan)
Recently, we reported that Al-doped ZnO (AZO)/non-doped Zn1-XMgXO/Cu2O heterojunction solar cells with conversion efficiencies over 4% were fabricated with a Mg content (Mg/Zn+Mg atomic ratio : X) in the range of 0 to 0.09 using Cu2O sheets that had been prepared by a thermal oxidization of copper sheets. This paper describes heterojunction solar cells with high efficiencies, over 5%, that were fabricated by inserting n-Ga2O3 instead of n-Zn1-XMgXO, producing n+-AZO/n-Ga2O3/p-Cu2O. The Cu2O sheets, with electrical properties such as resistivity on the order of 103 Ωcm, hole concentration on the order of 1013 cm-3 and Hall mobility above 100 cm2/Vs, were prepared by a thermal oxidization of copper sheets under appropriate conditions. Non-doped Ga2O3 thin films were prepared on non-intentionally heated Cu2O sheets by a pulsed laser deposition (PLD) using an ArF excimer laser in a camber where O2 gas was being introduced at partial pressures in the range from 0 (vacuum) to 3 Pa. The photovoltaic properties of the fabricated Cu2O-based solar cells were evaluated under AM1.5G solar illumination (100 mW/cm2) at 25oC. It was found that the obtainable photovoltaic properties such as conversion efficiency (η), open circuit voltage (VOC), short-circuit current density (JSC) and fill factor (FF) in the AZO/Ga2O3/Cu2O heterojunction solar cells were strongly dependent on the thickness as well as the deposition conditions of the Ga2O3 films. The external quantum efficiency (EQE) obtained in AZO/Ga2O3/Cu2O heterojunction solar cells was found to be greater at wavelengths below approximately 400 nm than that obtained in AZO/Zn1-XMgXO/Cu2O at equivalent wavelengths. In addition, the obtainable photovoltaic properties in AZO/Ga2O3/Cu2O heterojunction solar cells improved considerably as the O2 partial pressure was increased during the PLD, reaching maximum values at approximately 1.7 Pa, and then decreased as the pressure was increased further. All the maximum values for VOC, JSC, η and FF obtained in AZO/Ga2O3/Cu2O heterojunction solar cells were higher than those obtained in AZO/Zn1-XMgXO/Cu2O heterojunction solar cells. An efficiency over 5% was obtained in an AZO/Ga2O3/Cu2O heterojunction solar cell fabricated using a Ga2O3 thin-film layer prepared with a thickness of 50 nm under an O2 partial pressure of 1.7 Pa. It can be concluded that a thin Ga2O3 film can serve as an excellent n-type semiconductor layer in Cu2O-based heterojunction solar cells.
CP23 Influence of Crystallographical Properties on Obtainable Texture-etched Surface Structure in Transparent Conducting Impurity-doped ZnO Thin Films
Toshihiro Miyata, Jun-ichi Nomoto, Tuyoshi Fujita, Tadatsugu Minami (Kanazawa Institute of Technology, Japan)
For impurity-doped ZnO thin films to be suitable for transparent electrode applications in Si-based thin-film solar cells, they must attain a significant scattering of incident visible and near-infrared light by the textured surface structure formed on the films. This paper describes the relationship between the crystallographical properties and the obtainable texture-etched surface structure in transparent conducting impurity-doped ZnO thin films. Al-, Ga-, or B-doped ZnO (AZO, GZO, or BZO) thin films were prepared with a thickness of 1-2 μm on OA-10 glass substrates at 200oC by pulsed laser deposition using an ArF excimer laser and/or magnetron sputtering deposition (MSD). AZO, GZO, and BZO thin films were prepared by PLD. AZO and GZO thin films were also prepared by direct current (dc) MSD (dc-MSD) and radio frequency power superimposing dc-MSD (rf+dc-MSD). To obtain the light scattering characteristics suitable for applications in thin-film solar cells, we carried out surface texturing of the samples by wet-chemical etching in a 0.5% HCl solution. We also performed surface morphology observations and optical property measurements that included angular resolved scattering (ARS) and haze values on surface-textured impurity-doped ZnO thin films. For the crystallographical property evaluation, out-of-plane or in-plane XRD and X-ray locking curve measurements were carried out for the impurity-doped ZnO thin films. For example, for AZO thin films prepared by rf+DC-MS, the following characteristics were found to be considerably dependent on the crystallographical properties of the films: the etching rate, the surface texture structure formed by wet-chemical etching, and such resulting light scattering properties as the ARS data and the haze values. Note that the ARS intensity at scattering angles from 40 to 80 degrees and haze values at longer wavelengths significantly increased as the c-axis orientation of the AZO films improved, as evidenced from the full width at half maximum (0002) of the locking curve of the AZO films, regardless of the deposition methods. In addition, the AZO films exhibited lower ARS intensity and haze values, as evidenced from the observations of (100), (101), (110), (200), and (201) diffraction peaks in the in-plane XRD patterns. In contrast, the AZO films exhibited higher ARS intensity and haze values, as evidenced from the observations of only (100), (110), and (200) diffraction peaks. These results suggest that the influence of the crystallographical property on the obtainable texture-etched surface of the AZO films described above can be mainly attributed to such crystallinity improvement as orientation and crystallite size.
CP24 Co-Sputtering and RTA Process for Preparation of CIGS Thin Films Using Gallium, Indium and Copper Diselenide Alloy Targets
Esso-ekazi Bleza, Seongha Oh, Geum-Bae Cho, Nam-Hoon Kim (Chosun University, Korea)
Thin-film solar cells with copper-indium-gallium-diselenide (CIGS) absorber offer the high-efficiency of performance, which are considered as the most promising photovoltaic devices in the new and renewable energy industry with the efficiency up to 20%. The CIGS thin films are generally manufactured by the selenization process in selenium-containing gas after sputtering method or the three-stage process in evaporation method with four sources of copper, indium, gallium, and selenium pure elements. However, the above mentioned methods have some critical problems for mass-production including process complexity with costly equipment. A novel non-selenization method was proposed and demonstrated to prepare CIGS thin film sputtered by using gallium, indium and copper diselenide alloy targets with multilevel stacked structure and rapid thermal annealing (RTA) process in our previous study. In this study, the magnetron co-sputtering method was performed with three sputtering guns for using gallium, indium and copper diselenide alloy targets followed by RTA treatment. The powers in each sputtering gun were varied for adjusting the stoichiometry in CIGS thin films. The crystal structure of the RTA-treated CIGS thin films was analyzed by using X-ray diffraction (XRD) and Raman scattering. A secondary ion mass spectroscopy (SIMS) depth profile was employed to examine the chemical states of the RTA-treated CIGS thin films. The optical properties and electrical characteristics of the RTA-treated CIGS thin films were analyzed by using UV-visible spectrophotometer and a Hall Effect measurement system. Acknowledgement: This research was financially supported by the Ministry of Education, Science Technology (MEST) and National Research Foundation of Korea(NRF) through the Human Resource Training Project for Regional Innovation.
CP25 Analysis of Coatings in Matrix of Conformation Fasteners in Stainless Steel Austenitic
Wilmar Mattes, José Paiva Junior (Centro Univesitário Catolica de Santa Catarina, Brazil)

This work was to study to test the application of three coatings, deposited in arrays conformation, for the manufacture of fastening elements in austenitic stainless steels 302 HQ. One of the problems that occur during the forming process is the adhesion of conformal material (stainless steel 302HQ), forming the arrays were coated with TiN, TiAlN and TiAlSiN. Forming Matrices were machined by a polishing process, to reduce the roughness. To analyze the behavior of the coatings were used the following tests: integrity analysis tools through superficial roughness; tests microstructures characterization by scanning electron microscope (SEM); assay adhesion of the coating, embossing tests; Metallographic analysis: the substrate tool Steel AISI D6, the lines of deformation of a screw formed by the first matrix tested in a tool sectioned regions of: substrate layer of the coating. It was determined that the matrices must have a roughness pattern to avoid wear and improve the process. In the forming process is crucial that no flaws, a variable that must be controlled is the alignment between the tool and blank.

CP26 Influence of Rapid Thermal Annealing Treatment on Transparent Conducting Impurity-Doped ZnO Thin Films for Thin-Film Solar Cell Applications
Jun-ichi Nomoto, Toshihiro Miyata, Tadatsugu Minami (Kanazawa Institute of Technology, Japan)
This paper describes an investigation of the influence of a rapid thermal annealing (RTA) treatment on various properties of transparent conducting impurity-doped ZnO thin films prepared by magnetron sputtering depositions that was conducted in an effort to develop thin-film transparent electrodes suitable for thin-film solar cell applications. Impurity-doped ZnO thin films such as Al- or Ga-doped ZnO (AZO or GZO) were deposited with a thickness of 2 μm on OA-10 glass substrates at a temperature of 200 oC. The Hall mobilities in both the AZO and GZO films doped with impurity contents up to approximately 1.5 at.% always decreased after heat treatment with RTA at 500oC for 5 min in air, which is in contrast to the slight increase of the Hall mobilities exhibited in films doped with an impurity content above approximately 1.5 at.%. In addition, the heat treatment with RTA was found to improve the crystallinity in these films, as evidenced from X-ray diffraction analyses. The heat treatment with RTA always decreased the carrier concentration in both the AZO and GZO films, irrespective of the doped impurity content, whereas the resulting carrier concentration in as-deposited AZO and GZO thin films increased as the impurity content doped into the films was increased. In addition, the etch pit size developed in AZO and GZO films that were surface textured by wet-chemical etching in 0.2 mol./l HCl at 25oC tended to increase as the content of impurity doped in the films was increased up to approximately 2.5 at.%; however, the etch pit size obtained in GZO films decreased as this content was increased further. It should be noted that the heat treatment with RTA resulted in considerably enhanced etch pit size in these films, irrespective of the kind and content of doped impurity. As a result, in the films that were wet-chemically etched after being heat treated with RTA, the transmittance and the haze value in the near infrared range of 800-1200nm both increased as the size of the etch pits increased. The improvement of optical properties described above is attributed to the decrease of carrier concentration as well as the increase in etch pit size that result from the RTA treatment improving the crystallinity. In addition, it should be noted that the improvement in the transmittance and the haze value obtained in texture-etched impurity-doped ZnO thin films doped with an appropriately lower impurity content as well as heat treated with RTA is sufficient to enable the use of the surface textured AZO and GZO films described above for thin-film transparent electrode applications in thin-film solar cells. This work was supported by the NEDO.
CP29 Hole Trapping-induced Anomalous Gate Current Hump after Dynamic Negative Bias Stress in p-MOSFETs with HfO2 and HfxZr1-xO2/Metal Gate Stacks
Szu-Han Ho (National Chiao Tung University, Taiwan, Republic of China); Ting-Chang Chang (National Sun Yat-Sen University, Taiwan, Republic of China); Tseung-Yuen Tseng (National Chiao Tung University, Taiwan, Republic of China)
This letter investigates an anomalous hump in gate current after dynamic negative bias stress (NBS) in HfO2 and HfxZr1-xO2/metal gate p-channel metal-oxide-semiconductor field-effect transistors which is found to be a result of hole trapping in high-k bulk. Measuring gate current under initial for body floating and source/drain floating conditions isolates hole current flowing from the source and drain. The fitting of the gate current-gate voltage characteristic curve demonstrates that the Frenkel-Poole mechanism dominates the conduction. Next, fitting the gate current after dynamic NBS confirms Frenkel-Poole, tunneling, then a second Frenkel-Poole mechanism region. These phenomena can be attributed to hole trapping in high-k bulk and the electric field following Ehigh-k εhigh-k = Q + Esio2εsio2. To further understand gate current, Zr-undoped and 8% ~ 10% Zr-doped in high-k bulk devices were used for comparison. All the results conform to the hump generation condition JTunneling << JFrenkel-Poole.
CP30 Temperature Dependent Instability of Drain Bias Stress in Amorphous Indium-Gallium-Zinc-Oxide Thin Film Transistors
GengWei Chang (National Chiao Tung University, Taiwan, Republic of China); Ting-Chang Chang (National Sun Yat-Sen University, Taiwan, Republic of China); Ya-Hsiang Tai (National Chiao Tung University, Taiwan, Republic of China); Yong-En Syu (National Sun Yat-Sen University, Taiwan, Republic of China)
This paper investigates the behavior of drain bias stress at high temperature for amorphous Indium-Gallium-Zinc-Oxide thin film transistors (a-IGZO TFTs). The abnormal electrical characteristics exhibit a two-stage degradation behavior during drain bias stress, and are explained by the energy band diagrams . The thermal-excited non-uniform hole trapping in the drain region induces drain side barrier lowering and causes an apparent hump phenomenon in the subthreshold swing. This phenomenon only appears at high temperature, above 400K, and is experimentally verified. This work also employs capacitance-voltage measurement to confirm the proposed mechanism. Moreover, we applied a technology computer-aided design (TCAD) simulation system to further clarify the mechanism of degradation behaviors.
CP31 Temperature Dependence on Positive Gate Bias Instability in HfO2/TiN p-MOSFETs
HuaMao Chen (National Chiao Tung University, Taiwan, Republic of China); Ting-Chang Chang (National Sun Yat-Sen University, Taiwan, Republic of China); Ya-Hsiang Tai (National Chiao Tung University, Taiwan, Republic of China); WenHung Lo (National Sun Yat-Sen University, Taiwan, Republic of China)
This work studies positive gate bias temperature instability (PBTI) in high-k/metal gate p-channel MOSFETs. We found that device with different nitrite (N) concentration of metal gate shows contrary trend of Vth shift under high temperature during stress. Accordingly, off-state gate leakage (OSGL) is measured to analyze the conduction mechanism of carrier during PBTI. For device with less N, PBTI-induced Vth shift is attributed to Poole-Frankle mechanism under high temperature, since Vth shift and OSGL decrease as temperature increases. This is because carriers could conduct toward gate electrode likely instead of being trapped in high-k bulk, resulting in insignificant Vth shift as high temperature. However, for device with more N, the mechanism of Vth shift under high temperature is associated with thermal emission, since Vth shift and OSGL show a contrary tendency with temperature. According to that, it indicates that trapping carriers in high-k layer could be supplied by thermal emission continuously.
CP32 Investigation of Random Telegraph Signal in PD SOI nMOSFETs between Moderate and Strong Inversion Region
Ching-En Chen (National Chiao Tung University, Taiwan, Republic of China); Ting-Chang Chang, Bo You (National Sun Yat-Sen University, Taiwan, Republic of China); Tseung-Yuen Tseng (National Chiao Tung University, Taiwan, Republic of China)
This paper investigates the random telegraph signal (RTS) with partially depleted silicon-on-insulator n-channel metal-oxide-semiconductor field effect transistors (PD SOI nMOSFETs). It was found that the relative amplitude of drain current RTS (ΔID/ID) with different gate voltages reveal a steep decrease in moderate inversion and a temperate decrease in strong inversion. According to drain current RTS (ID-RTS) at different temperatures, the active energies of capture cross section could extract by Shockley-Read-Hall (SRH) model at different gate voltages. These active energies correspond to non-radiative multiphonon (NMP) barrier heights and then provide a fundamental physical model of oxide traps for ID-RTS from moderate to strong inversion region.
CP33 Self Current Compliance Bipolar Resistance Switching Characteristics for Nonvolatile Memory Application
Hsueh-Chih Tseng (National Sun Yat-Sen University, Taiwan, Republic of China)

This study investigates the self current compliance bipolar resistance switching behaviors of resistive random access memory with ITO/SiOx:Gd/TiN and Pt/SiOx:Gd/TiN devices. Generally, because the set process of filament-type resistance switching has to accompany a current compliance, the transistor is a common element to achieve the function of current compliance (1T-1R structure). However, the 1T-1R structure suffers from certain physical limitations from its continual scaling down limit. Hence, a self-formation current compliance structure should be developed. ITO/SiOx:Gd/TiN structure can exhibit a self current compliance property due to an interface formation between ITO/bulk, which can form a self-build series resistor to achieve the current compliance. Moreover, the electroforming process with a higher current compliance can compose a better self-formation current compliance property, one which can reduce the operation current and voltage. Additionally, the Pt/SiOx:Gd/TiN device exhibits an interface-type bipolar resistive switching, one which has not only a size effect, but also a but also a lower operating current. The resistance transitions are due to the variation in conductance of the switching layer, which also shows a self current compliance phenomenon. Finally, compared with 1T-1R structure, the self-formation current compliance can reduce the cost of the fabrication process.

CP35 Study of the Surface Chemical Composition and Evaluation of Corrosion Resistance of BiXTiYOZ Thin Films Deposited by RF Magnetron Sputtering
JoséEdgar Alfonso, JhonJairo Olaya, Manuel Pinzón (National University of Colombia, Colombia); JoséFrancisco Marco (CSIC)

Bismuth Titanate Oxide (BixTiyOz) compounds have been the subject of many studies due to their ferroelectric, piezoelectric and optical properties, which make them interesting material s for the fabrication of optical devices, ferroelectric memories and lead-free piezoelectric sensors and actuators. However, there have been few studies on the corrosion resistance of these materials . Therefore, the main aim of this work is to report on our preliminary data on the corrosion resistance of BixTiyOz thin films and to correlate the observed results with their chemical surface compositionand crystallinity

The BixTiyOz thin films were deposited by RF magnetron sputtering onto stainless steel and titanium alloy (Ti6Al4V) substrates. The structural properties were studied by x-ray diffraction (XRD); the surface chemical composition was determined by x-ray photoelectron spectroscopy (XPS) and the corrosion resistance was evaluated by potentiodynamic polarization Tafel tests.

The XRD preliminary results i ndicate that the films are amorphous or poorly crystalline in nature . The XPS analysis show that the uppermost part of the deposited film s is mainly composed by bismuth oxide (Bi2O3) and titanium oxide (TiO2) and the corrosion tests show that the current density is lower by two orders of magnitude than that shown by the uncovered substrates.

CP36 Light Extraction Enhancement by Metallic Photonic Crystal Nanostructures Embeded in Gallium Nitride Diodes
Gwomei Wu (Chang Gung MemoUniversity, Taiwan)
Higher energy efficient light-emitting diodes (LED) have been highly demanded as green energy alternative in the market place. The gallium nitride LED provides blue light source, and is emerging with solid-state lighting technology. In this report, metallic photonic crystal nanostructures have been embedded in gallium nitride diodes to increase the light extraction efficiency of LED devices. We employed finite-difference time0domain (FDTD) method to simulate the metallic photonic crystal nanostructures with the relevant parameters, such as periodicity arrangement, filling factor, location, space structure and dielectric constant. Not only photonic crystal structures can increase the efficiency for light extraction by optical confinement effects, but also surface plasmon would localize the electromagnetic field enhancement phenomenon that increases the efficiency. The metallic photonic crystals have been embedded on the LED surface, inside the transparent conducting layer, and inside the p-GaN layer. The results showed that the extraction efficiency of the embedded LED could significanly increase by about 8% to 12%.
CP37 Effects of Intermediate GAZO Layer Thickness on the Properties of GAZO/Ag/GAZO/Ag/GAZO Film
YuSup Jung, HyungWook Choi, KyungHwon Kim (Gachon University, Republic of Korea)
The Ga-Al doped ZnO (GAZO)/Ag/GAZO/Ag/GAZO transparent conductive multilayer film were prepared by facing targets sputtering (FTS) methods at room temperature. The multilayer thin films consisted of Ag metal thin film layers and transparent conductive GAZO thin films layers. The fabricated GAZO/Ag/GAZO/Ag/GAZO multilayer thin films have a low sheet resistance and a high transmittance in the visible range. As a results, sheet resistance and average transmittance in visible range of the GAZO/Ag/GAZO/Ag/GAZO multilayer thin film with optimal layer thicknesses (50/12/75/12/50 nm) exhibits 2.7 Ω/sq and 82% and the figure of merit of exhibits 4.9х10-2 Ω-1 (T: 0.82 and Rsh:2.7Ω/sq) keywords: GAZO/Ag/GAZO/Ag/GAZO, Multilayer thin film, Facing Targets Sputtering
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