ICMCTF2016 Session CP: Symposium C Poster Session

Thursday, April 28, 2016 5:00 PM in Room Grand Hall

Thursday Afternoon

Time Period ThP Sessions | Topic C Sessions | Time Periods | Topics | ICMCTF2016 Schedule

CP-2 Novel Nitride Thin Films in the Sc-Nb-N System for Thermoelectric Applications
Arnaud Le Febvrier, Sit Kerdsongpanya, Per Eklund (Linköping University, IFM, Sweden)

In the last few years, there has been an important interest on the transition metal nitrides for their potential for thermoelectric applications. Indeed a recent theoretical study predicted the potential of the AMN2 (A = Ca, Ti, Sr and M = Ti, Zr, Hf) layered nitride materials to exhibit a high Seebeck coefficient and good electrical conductivities[1]. Another study on a first principles calculations of the phase stability of the Sc based nitride materials, which already showed its potentialities for thermoelectric applications[2], demonstrated a very low mixing enthalpy of the ScMN2 phase (M = Nb, Ta)[3]. Furthermore, nitride alloy thin films is one of the strategy for lattice thermal conductivity reducing. Indeed, ScN exhibited a low thermoelectric figure of merit (ZT) about 0.2-0.3 at 800°C mainly due to the high total thermal conductivity[4]. Insertion of heavy elements by alloying may introduce phonon scattering therefore reduce the thermal conductivity and increase the ZT.

With the same perspective, our experimental study is focused on the deposition of the thin films in the Sc-Nb-N system by co-magnetron sputtering on sapphire and MgO substrates. The different parameters of depositions (power, pressure, Ratio Ar/N2 and temperature) played an important role on the phase formation. The system Sc-Nb-N can be found in different phases from the pure corresponding nitrides, the disordered solid solution and the AMN2 phases. The morphology and structural properties of the Sc-Nb-N thin films were investigated and their effects on the electrical and thermoelectric properties were evaluated.

[1] R. Al Rahal Al Orabi et al, Journal of Materials Chemistry A 3 (2015) 9945.

[2] S. Kerdsongpanya et al, Applied Physics Letters 99 (2011) 232113.

[3] S. Kerdsongpanya et al, Journal of Applied Physics 114 (2013) 073512.

[4] P.V. Burmistrova et al, Journal of Applied Physics 113 (2013) 153704.

CP-3 Development of High Temperature Mold Process for Sand Casting with Thin-Wall and Complex Shape
Eun-Hee Kim, Geun-Ho Cho, HyeYeoung Park, HyunHee Choi, Yeon-Gil Jung (Changwon National University, Republic of Korea)
A mold process has been developed for fabricating the mold endured under a high temperature of 1000 oC, resulting in preparing the casting products having the thin-wall of below 5 mm and complex shape. In the new mold process, the inorganic binder composed of tetraethyl orthosilicate (TEOS) and sodium methoxide (NaOMe) was applied to the conventional sand mold process. In addition, two processes were employed to improve the thermomechanical properties of mold; the inorganic binder was infiltrated onto the mold sample formed with organic binder in process I, and the mold sample was prepared with the organic binder using powders coated with the inorganic binder in process II. The mold prepared through process II showed the higher fracture strength than that prepared by process I, caused by the higher glassification efficiency. Especially, in the case of mold prepared with an artificial sand, the strengths before and after heat-treatment were measured as 9.6 ± 0.5 MPa and 9.1 ± 0.9 MPa, respectively. The thermal expansion ratios of molds were detected within 2.29 ~ 2.47%, independent of process and starting material. High chrome iron was well casted in the mold prepared with the inorganic binder and its castability has been verified.
CP-8 Characterization of Cu-meshes Coated by Graphene and Carbon Nanotubes via Electrophoretic Deposition
Young-Jin Hwang, Bu-Jong Kim, Jong-Seol Park, Jin-Seok Park (Hanyang University, Republic of Korea)

Transparent conducting electrodes (TCEs) have attracted great interest because of their wide applications in solar cells, liquid crystal displays, organic light-emitting diodes, and touch screens. As an integral part of the flexible versions of these electronic devices, the flexibility of the TCEs is essential. Despite the exceptional optoelectronic properties of the conventional indium–tin-oxide (ITO) thin films as TCEs, they suffer from considerable drawbacks basically due to their brittle nature. This has motivated research for alternative materials such as carbon nanotubes (CNTs), graphene, conducting polymers, silver nanowires, and metal meshes. Among these, metal meshes are considered as the most promising replacement for ITO becase of their excellent optical and electrical properies. However, metal meshes have visibility issues because of high reflectance of metals. Also, few studies on the improvement of reflectance properties of metal meshes have been reported in literature. Furthermore, the sheet resistance of metal may increase greatly when exposed to air for a long time due to the oxidation of metals. To address these problems, several methods, such as embedment of metal meshes in a polymer matrix or additional coating of protective layers on metal meshes, have been investigated. However, the embedment of metal meshes and coating of metal oxide protective layers need to be processed at high temperatures. Also, the polymer-based protective layers are typically very thick and electrically insulating materials.

In this study, we present hybrid-type flexible TCEs which possess desirable characteristics in visibility, stability against oxidation, and flexibility. The hybrid-type TCEs were fabricated by sputtering and patterning copper (Cu) meshes on glass and polyethyllene terephthalate (PET) substrates, and then coating graphene or CNTs via eletrophoretic deposition (EPD). For the fabricated TCEs, their surface morphologies (via field-emission scanning electron microscopy), electric sheet resistances (using a non-contact sheet resistance measurement equipment), visible-light transmittances and reflectances (using a spectrum colorimeter), kinds of chemical bonds (via x-ray photoelectron spectroscopy), and contact angles (using a dynamic contact angle measurement system) were characterized and compared in terms of the graphene and CNTs used. The stability test was conducted by measuring the changes in their sheet resistances for a period of 250 h under the conditions of 85°C-temperature and 85%-humidity. Also, the bending test was performed up to 10,000 times with the curvature radius of 5 mm.
CP-9 Effects of Hafnium Doping on the Properties of Aluminum-Zinc-Oxide Films and Characteristics of Thin Film Transistors
Sang-Hyuk Lee, Hyun-Sik Jun, Ju-Hee Park, Jin-Seok Park (Hanyang University, Republic of Korea)

Recently, zinc-oxide based thin-film transistors (ZnO-TFTs) have shown specific characteristics for transparent displays. M ost of the successful ZnO-based TFTs incorporate indium (In) such as indium zinc oxide (IZO) and indium gallium zinc oxide (IGZO). However, In is expensive and relatively rare on Earth. Thus, some researchers have recently reported experimental results which indicate In-free oxide semiconductors, such as silicon-zinc-oxide (SZO), aluminum-zinc-oxide (AZO), and gallium-zinc-oxide (GZO). It is believed that the element aluminum (Al, group III) acts as an effective donor in the ZnO lattice because they may be substitutionally placed on Zn sites. Thus, they will then enhance the carrier concentration and conductivity. Also, hafnium (Hf, group IV) is stable at high temperature stress and bias stress in the ZnO lattice. Until now, however, there has been a dearth of comprehensive studies on the hafnium-aluminum-zinc-oxide (HAZO) films and their applications for TFTs.

In this study, HAZO films were deposited on glass and Si substrates via room-temperature co-sputtering where the electric power applied to the aluminum-zinc-oxide target was fixed to 100 W and the electric power applied to the hafnium-oxide target varied from 0 W to 60 W. Other deposition conditions were a working pressure of 10 mTorr and a gas flow rate of 60 sccm for Ar. The structural, optical, and electrical properties of HAZO films were evaluated using various methods, such as X-ray diffraction (XRD), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), energy dispersive x-ray spectroscopy (EDS), UV/visible spectrophotometry, and Hall measurement. All the properties measured were characterized in terms of the deposition conditions of HAZO films. Moreover, TFTs using the HAZO films as the channel layer were fabricated and their device characteristics were analyzed. The experimental results obtained in this study have confirmed that HAZO thin films have the potential for the channel layer of transparent TFTs.

CP-11 Effect of Ga Content on Optoelectronic and Magnetic Properties of (Ga, Co) Co-doped ZnO Films by Radio Frequency Magnetron Co-sputtering
Sheng-Chi Chen, Chao-Feng Lu, Chung-Hsien Wang (Ming Chi University of Technology, Taiwan, Republic of China); Chia-Lung Tsai (Industrial Technology Research Institute, Taiwan, Republic of China); Chao-Kuang Wen (National Taiwan University, Taiwan, Republic of China); Yi-Keng Fu (Industrial Technology Research Institute, Taiwan, Republic of China); Tung-Han Chuang (National Taiwan University, Taiwan, Republic of China)

Diluted magnetic semiconductors (DMSs) based on ZnO have attracted a great deal of attention due to their potential application in magnetic semiconductor devices. In particular, they are predicted to display ferromagnetic properties at Curie temperature above room temperature and have large magnetization. (Ga, Co)-ZnO films for use as DMSs have been fabricated using various techniques, including molecular beam epitaxy (MBE) [1], pulsed laser deposition (PLD) [2] and inductively coupled plasma enhanced physical vapor deposition (ICP-PVD) [3], etc. However, there are very few reports about (Ga, Co)-ZnO thin films deposited using radio frequency (rf) magnetron sputtering .

In this study, (Ga, Co)-ZnO [CoxGayZn(1-x-y)O] films with different Ga contents are co-sputtered on glass substrates by rf magnetron sputtering. The x content [Co/(Ga+Co+Zn)] in the films is ~ 0.05. The content of y [Ga/(Ga+Co+Zn)] varies from 0 to 0.032. Using Hall effect analysis, the resistivity (ρ) of the film is 42.9 Ω-cm when y content is 0. When the content of y increases to 0.032, the ρ value drops greatly to 4.93 × 10-3 Ω-cm. In photoluminescence analysis, all the oxygen-rich (Ga, Co)-ZnO films contain acceptor-like defects. In magnetic properties analysis, when low Ga contents are doped and with low carrier concentration range (< 2.48 × 1017/ cm3), saturation magnetization (Ms) is established by Bound Magnetic Polaron (BMP) due to defects and magnetic atoms in the films. However, Ms is created by the free electrons and Co atoms that produce the exchange coupling effect when high Ga concentration is present in the films and in high carrier concentration range (> 7.34 × 1018/ cm3). In the transition zone, since the two mechanisms mentioned above are overlapped and exchanged, Ms value drops when the carrier concentration in the films increases from 2.48 × 1017/ cm3 to 7.34 × 1018/ cm3.

Keywords:rf magnetron co-sputtering, diluted magnetic semiconductor s, (Ga, Co) co-doped ZnO films, optical properties, electrical properties, magnetic properties.


[1] Zhonglin Lu, Hua-Shu Hsu, Yonhua Tzeng, Fengming Zhang, Youwei Du and Jung-Chun-Andrew Huang , Appl. Phys. Lett. 95 (2009) 062509.

[2] Liping Zhu, Zhigao Ye, Xuetao Wang, Zhizhen Ye and Binghui Zhao, Thin solid films 518 (2010) 1879-1882.

[3] Xue-Chao Liu, Zhi-Zhan Chen, Bo-Yuan Chen, Er-Wei Shi and Da-Qian Liao, J. Cryst. Growth 312 (2010) 2871-2875

CP-12 C-Sputtering Simulation (CO-SS) of the Sputtering Yield Amplification of Al, C and Si
Julio Cruz, Stephen Muhl (Instituto de Investigaciones en Materiales - UNAM, Mexico); Eduardo Andrade (Instituto de Física-UNAM, Mexico); Óscar de Lucio (Instituto de Física -UNAM, Mexico); Emmanuel Garcés (Wolfram Research Inc., Mexico)

Co-sputtering simulation (CO-SS) of the sputtering yield amplification of Al, C and Si

Sputtering yield amplification is a phenomenon that was discovered by S. Berg et al. in 1991. This phenomenon can occur during the preparation of thin films by co-sputtering of a target composed of two different materials. If the difference in the atomic weight of the elements of the two parts of the target is large, then it has been observed that the sputtering yield of the lightest element can be greater than the normal value. However, at present there is no adequate phenomenological or theoretical explanation of this phenomenon.

The co-sputtering simulation freeware, CO-SS, was developed by the authors to simulate the spatial variation and composition of the deposition by magnetron sputtering and co-sputtering. In this study thin films of Al/Ti, C/W and Si/W were produced to study the modification of the sputtering yield both experimentally and by modelling using CO-SS. The 4” x ¼” sputtering targets were of high purity Al, C and Si and the sputtering conditions for all deposits was maintained at 20 sccm of argon, a gas pressure of 30 mTorr (4 Pa) and a plasma power of 40 watts. A series of films was prepared of the pure metal or with 1, 2 or 3 small pieces (0.7 X 2.5 cm) of the second material (Ti or W) placed on the racetrack directly above the 3” x 1” glass substrates. The substrates were placed such that they received material from both the uncovered and covered parts of the racetrack. The spatial variation of the thickness and composition of the films was determined by profilometer and the 4He RBS technique, respectively. The results showed the existence of the previously mentioned sputtering yield amplification of Al, C and Si.

* Work partially supported by DGAPA IN102015 project

CP-14 Study of Perovskite Solar Cells Prepared by Low-Temperature Solution Techniques
Gwomei Wu (Chang Gung University, Taiwan)
The rapid advancement in perovskite solar cell technology has attracted much attention in recent years. It has been noted that some perovskite solar cells prepared from low-temperature solution process can provide the potential for less expensive technnique than the prevailing high-temperature process. However, the photoelectric conversion efficiency needs to be further investigated and improved. In the two-step metnod, it is important to control the film quality of lead iodide. During the preparation, zinc oxide solution was coated on etched ITO glass by spin-coating first. After baking at 180oC for 30 minutes to dry, lead iodide solution was further spin-coated, the baked at 70OC for 5 minutes. The perovskite structure was produced by doped MAI solution, then hole transport spiro-OMeTAD on top, finally molybdenum trioxide and silver for electrodes. In this study, we changed the standing time after spin-coating the lead iodide layer. The time was varied from 0 to 210 seconds, with 30 seconds for the interval. It has been ovserved that with the elongated standing time, the lead iodide particles would gather much bigger. The perovskite film under the condition of 150 seconds exhibited the smoothest surface. It also showed different crystallins phases with different standing time, as revealed by XRD analysis. It was also confirmed that the lead iodide film could affect the different perovskite. The experimental results showed improved photoelectric conversion efficiency of the device up to 11.45%. The electro-optical characteristics will be presented and further discussed.
CP-18 Fabrication of P-type ZnO by Annealing Zn3N2 Grown by RF Magnetron Sputtering
Muhammad Haider (King Fahd University of Petroleum and Minerals, Saudi Arabia)
Zn3N2 is an important material and recently has attracted attention because of its application in optoelectronics and renewable energy. Zn3N2 can also be used to form stable p-type ZnO by annealing Zn3N2 in oxygen environment. We have grown Zn3N2 thin films on silicon and fused silica substrates at 300 oC by RF magnetron sputtering. Films were grown at different N2:Ar pressure ratio of 0.20, 0.40, 0.60, 0.80 and 1.0. Growth at different N2 partial pressure has little effect on the surface morphology of the samples. All the samples have grain like surface morphology with average surface roughness ranging from 4-5nm. Zn3N2 samples are single crystalline with a major XRD peak at 2q value of 34.5o corresponding to Zn3N2 (321), whereas a relatively small peak can also be observed at 36.5o corresponding to Zn3N2 (004). Hall Effect measurements reveal that films are n-type semiconductors and the carrier concentration increases with the increase in N2 partial pressure during the growth. We have found that the films grown at N2/Ar ratio of 0.60 give rise to best films in terms of crystallinity and electronic properties. We then grew a few more films at N2/Ar ratio of 0.60 at 300 oC and then subsequently annealed them in oxygen atmosphere at different annealing temperature. We observed that the Zn3N2 films were transformed to ZnO and their optical, structural and electronic properties depend on the annealing temperature.
CP-19 Understanding Mechanisms of Adhesion of SiO2 Thin Film Deposited on a Polymeric Substrate
Caroline Ho, Joel Alexis, Loic Lacroix, Olivier Dalverny (Laboratoire Génie de Production ENIT-INP, France); Anita Dehoux, Francisco de Ayguavives, Pascale Lacan (Essilor R&D, France)

Ophthalmic lenses are made of thermoplastic polymeric substrates usually coated with functional treatments composed of 5 to 15 layers, ranging from micrometers to nanometers. The first treatment consists of a primer, conferring impact resistance properties to the lens. A hardcoat with nanoparticles, is then deposited on top of this primer, bringing anti-scratch properties to the system. Both primer and hardcoat are within the micrometer scale and are deposited by wet chemical methods. Nanometric anti-reflective stacks are then evaporated onto the hardcoat, to enhance wearers’ comfort.

Each of these interfaces may lead to delamination due to poor adhesion, and therefore affect the vision and comfort of wearers. The interface between the anti-reflective stack and the hardcoat is particularly sensitive because of chemical and mechanical contrast of its materials.

The ultimate goal is to better understand mechanisms that lead to loss of adhesion between the SiO2 layer deposited on the anti-scratch hardcoat. Emphasis is first placed on characterizing mechanical properties of materials composing the interface. In parallel, an applicable and effective method to quantify adhesion needs to be determined and tested. The use of nano-indentation and AFM; not only to obtain information on surface’s topography, but also to access mechanical and adhesion properties, is under study. Micro-tensile tests to acquire interfacial cracking energies, are considered and will be performed as well.

CP-20 Electron-Beam Deposited Multilayered HfO2/Mo/HfO2 Devices for Energy Efficient Window Applications
Juan Gomez (The University of Texas at El Paso, USA)

Heat mirrors are defined as transparent multilayer structures that transmit visible light and reflect infrared radiation coming from the solar spectrum. In addition, heat mirrors can generate significant energy savings in buildings by reducing the amount of heat absorbed by windows. The present work focused on the heat mirrors based on three layer structures composed of dielectric/metal/dielectric (D/M/D) materials. Studies were made with HfO2 dielectric material and Mo for the metal. HfO2/Mo/HfO2 multilayered devices have been deposited using electron beam evaporation. The effect of variable Mo thickness on the efficiency of HfO2/Mo/HfO2 multilayered devices is evaluated. Unheated substrates were employed with HfO2 layer thickness 45 nm and 25 nm while varying the Mo metal interlayer thickness in the range of 9-20 nm. The optical properties of the films reveal a higher transmittance (%) of the films in the infrared (IR) to the near infrared (NIR) region, whereas it reduces in the visible region suggesting a more feasible application for these devices in cold environments for heat collection. A detailed analysis of the optical constants i.e. refractive index, band gap energy, and absorption coefficient, are evaluated for HfO2/Mo/HfO2 multilayered devices. Comparison of the data will be presented and discussed to determine the optimum Mo interlayer thickness and feasibility of the heat mirror for warm or cold environments.

CP-22 Highly Porous Carbon Films for High-rate Supercapacitor Electrodes
Aimin Wu, Chenchen Feng, Jiaxin Lv, Song Gao, Hao Huang (Dalian University of Technology, China)
Highly porous carbon film (PCF) on nickel foam was prepared successfully by microwave plasma-assisted chemical vapor deposition (MPCVD) with C2H2 as carbon source and Ar as discharge gas. The PCF is uniform and dense with 3D-crosslinked nanoscale network structure conformably coated on nickel foam, and possesses large specific surface area and high degree of graphitization, advantageous to electrical conductivity, ion contact and electrochemical stability, when used as the binder-free electrode material in an electrochemical supercapacitor. The electrochemical test results showed that the PCF prepared under the microwave power of 1000 W has an excellent electrochemical performance. It displays the specific capacitance of 62.75 F/g in 30% KOH aqueous solution with the current density of 2.0 A/g, and the specific capacitance remained 69% of the initial when the current density increased to 10.0 A/g. Besides, near-rectangular shape of CV curves exhibit typical characters of an electric double-layer capacitor and show high-rate capability due to its enhanced ionic diffusion and transportation ability.
CP-23 Surface Modified Carbon Nanofibers/MnO2 Composites for Use in Supercapacitor
Jyh-Ming Ting, Hsuan-Min Lin (National Cheng Kung University, Taiwan, Republic of China)

We report the synthesis of MnO2 nanoparticles (NPs) on carbon nanofiber (CNF) for use as electrode material in supercapacitor. The CNF was functionalized using acid treatment in solutions containing different H2SO4/HNO3 ratios. A microwave-assisted hydrothermal method was then used to grow MnO2 NPs on the surface modified CNF in a very short time (5 min). X-ray photoelectron spectroscopy (XPS) was employed to analysis the surface functionalized CNF. The morphology and microstructure of the resulting MnO2/CNF were observed using x-ray diffraction, field emission scanning electron microscopy, and high resolution analytical electron microscope. The electrochemical performance of the MnO2/CNF electrode was studied using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in 1 M Na2SO4 solution.

CP-24 Flexible and Transparent ITO/Ag Thin Films Fabricated by Using Dual-Facing Targets Sputtering at Room Temperature
SangMo Kim (Gachon University, Republic of Korea); MinJong Keum (Jusung Engineering Co., Republic of Korea); YouSeung Rim (University of California, Los Angeles, USA); KyungHwan Kim (Gachon University, Republic of Korea)

Double-stacked ITO/Ag thin films were fabricated on polyethersulfone flexible substrates by using dual-facing target sputtering at room temperature. Precise control for film thickness in ultrathin Ag films were successfully confirmed to obtain high conductivity and transparency in the visible ranges. Ag stacked ITO films showed higher transparency than only Ag film. It could be attributed to reduce the surface scattering of Ag film through the low-emissivity ITO film.

Optimized ITO (50 nm)/Ag (12 nm) films had the sheet resistance of 8 ohm/sq. and the transmittance of over 80 % at the visible range. Additionally, the mechanical durability of ITO/Ag films had low electrical degradation with below 10% compared with the pristine films.

CP-25 Structure and Photoluminescence of the Pt-coated V2O5 Nanowires by ALD Process
Chih-Chiang Wang (National Chung Hsing University, Taiwan, Republic of China); Han-Chang Shih (Chinese Culture University, Taiwan, Republic of China)

The V2O5 nanostructures have been known for the potential application of gas sensors, electrochromatic devices, critical temperature resistors, optical switch devices, etc., which is attributed to the reduction behavior and the reversible phase transitions. In this study, the V2O5/Pt core-shell nanowires were fabricated by the thermal evaporation via vapor-solid mechanism. Pt nanoparticles were subsequently coated on the V2O5 nanowires using the atomic layer deposition (ALD) process with 50, 100, and 150 cycles.

The FESEM images showed that the nanowire diameters were of 50-200nm with an aspect ratio of 102-103. The XRD pattern indicated the dominant peaks at (200), (001), and (002) belonging to the α-V2O5 phase of the orthorhombic crystal structure, the higher intensity and narrower FWHM, implying that the V2O5 nanowires posses a good crystallinity. The HRTEM image on a specific V2O5 nanowire of 108nm had the growth direction along the wire axis of [110] and the Pt coated V2O5 by ALD (150 cycles) showed a thickness of 4.5nm Pt-shell with the (111) plane. XPS spectra gave the result of the binding energy (eV) of the respective orbitals: 517(V2p3/2), 524(V2p1/2), and 530(O1s). The ΔE (13eV) between V2p3/2 and O1s indicated that the V2O5 phase was formed and also agreed with the XRD results. The binding energies of Pt4f7/2 at the ALD 50 cycles, 100 cycles, and 150 cycles were of 73, 72.8, and 71.6eV, which meant that the ratio of Pt/PtO increased with the increasing ALD cycles. The intensity of Pt4f7/2 increased with increasing ALD cycles confirmed that the Pt successfully coated on the V2O5 nanowires and thus the content of metallic Pt increased. The photoluminescence (PL) results showed that the peak indicated the original light emission of the V2O5 at 550nm without any shift by the effect of Pt. However, the intensity decreased due to the presence of the Pt contents. On the other hand, the emission peak that appeared at 466nm was caused by the Pt and its intensity increased with the increasing ALD cycles, also consistent with the result of the XPS.

CP-26 Characterization of Vanadium Oxide Thin Films with Different Stoichiometry Using Raman Spectroscopy
Chunzi Zhang, Qiaoqin Yang, Cyril Koughia, Fan Ye, Safa Kasap (University of Saskatchewan, Canada)

Vanadium oxides have been widely studied as “smart materials” because of their capability of going through a metal-insulator-transition. They are of considerable technological interests for applications in optoelectronics, ultrafast optical switches, electrochomic devices, and lithium microbatteries. However, vanadium-oxygen system is very complex due to the multivalency of vanadium, which makes preparation of vanadium oxide with single stoichiometry difficult. Structural characterization of vanadium oxides of different stoichiometry is highly desirable and would provide helpful guideline to both materials preparation and their structural characterization. Vanadium oxide thin films with different stoichiometry under various bonding states are successfully prepared by reactive sputtering with and without post oxidation or reduction and characterized using Raman spectroscopy. Characteristic Raman spectra of single phase and multiphases of VxOy including V2O3, VO2, V6O13, and V2O5 are presented and discussed. The results have demonstrated that high purity single phase oxides can be obtained under well controlled conditions.

CP-27 Spin-Glass Behavior and Exchange Bias Observed in YMn0.8Fe0.2O3 Thin Films
Samta Chauhan, Amit Kumar Singh, Paritosh Dubey, Ramesh Chandra (IIT Roorkee, India)
We have observed exchange bias as a consequence of spin-glass behavior in YMn0.8Fe0.2O3 thin film. The thin film has been deposited using pulsed laser deposition technique on Sapphire (0001) substrates. X-Ray diffraction confirms the hexagonal phase with c-axis orientation. The RMS surface roughness was found to be ~1.5 nm as confirmed by atomic force microscopy. The ZFC-FC curves were found to coincide and increase gradually up-to ~100 K, after which both the curves show an abrupt increase in magnetization. However, the two curves show a bifurcation near T = 40 K, after which the FC curve again increases with decreasing temperature. The ZFC curve shows a characteristic peak resembling to spin-glass like transition near T = 15 K (Tf). The ZFC curves obtained at different magnetic field (100, 1000 and 5000 Oe) show a shift in Tftowards lower temperature with increase in magnetic field thus obeying de-Almeida-Thouless line (Tf H 2/3), which is a characteristic of spin-glass systems. M-H hysteresis loops measured at 2 K indicate that the sample exhibit weak ferromagnetism. The M-H loops obtained after field cooling the sample with different applied magnetic field suggest the presence of exchange bias (EB) behavior. The EB was further confirmed by training effect measurements by repeated cycling of the sample.
CP-29 Effect of Gallium Doping on CdS Buffer Layer Properties and Corresponding CIGS Solar Cell Performance
Hyunmin Jung, Salh Alhammadi, Hyeonwook Park, WooKyoung Kim (Yeungnam University, Republic of Korea)

CdS thin film is a common material used as an n-type buffer layer in Cu(InGa)Se2 (CIGS), Cu2ZnSnS4 (CZTS) and CdTe thin film solar cells. In this study, pure CdS and Ga-doped CdS (Ga:CdS) were deposited onto soda lime glass, FTO, Mo-coated glass and CIGS absorber substrates using chemical bath deposition (CBD) technique. We used Gallium nitrate Ga(NO3)3 as gallium dopant source. The Ga doping concentration varied from 0.0005 to 0.002 M and the effect of gallium doping on CdS properties has been investigated. X-ray diffraction results confirmed that all CdS and Ga:CdS films have a cubic crystal structure with (111) plane preferred orientation. Also the lattice strain increased with increasing Ga doping concentration while the crystal size decreased with increased Ga contents. The UV-visible spectroscopy results showed that the transmittance was improved as Ga contents increase. Current-voltage characteristics of Cd and Ga:CdS measured by photoelectrochemical measurement demonstrated that Ga doping enhanced current but decreased impedance. Finally, the effect of Ga:CdS on CIGS solar cell performance will be discussed.

CP-30 Effects Of Deposition Conditions On The Characteristics Of Rf-Sputtered Lipon Protective Coatings For Lithium Aluminum Titanium Phosphate Solid Electrolytes
Hsin-Chun Lu, Zong-Han Li, Cheih-Yu Lei (Chang Gung University, Taiwan, Republic of China)

Implementation of RF-sputtered lithium phosphorus oxynitride (LiPON) films on lithium aluminum titanium phosphate (LATP) solid electrolytes as protective coatings to minimize the reaction between metallic Li electrodes and LATP solid electrolytes was explored. In addition, the effects of substrate temperature and N2 content in the working gas on the characteristics of the LiPON films and the performance and the chemical stability of the passivated LATP solid electrolytes were also investigated. It was found that regardless of the substrate temperature and the N2 content in the working gas employed in the work, LiPON films deposited by RF magnetron sputtering using lithium phosphate (Li3PO4) target under working gases with different N2 contents were amorphous. It was also found that the deposition rate of LiPON film increased when the N2 content in the working gas decreased from 100% to 25% while the deposition rate remained roughly the same when the substrate temperature increased from 50℃ to 250℃. Finally, LATP solid electrolytes passivated with LiPON protective layers indeed were more stable than the un-passivated ones when put in contact with metallic Li.

CP-31 Pre-formation of MoSe2 During Three-stage Co-evaporation of Cu(InGa)Se2 and its Effect on Solar Cell Performance
Sunmo Kwon, Jaseok Koo, WooKyoung Kim (Yeungnam University, Republic of Korea)

In Cu(InGa)Se2(CIGS)-based thin film solar cells, it is well known that the formation of MoSe2 at the Mo/CIGS interface is generally preferred because it gives electrically preferred ohmic contact between Mo and CIGS. During the deposition of CIGS light absorber, the thickness of MoSe2 should be controlled to maintain below 100 nm because it is reported that too thick MoSe2 layer has insulating property and thus lead to the reduction in cell performance. It is widely reported that the MoSe2 layer easily forms during the selenization of metallic Cu-Ga-In precursor in a H2Se gas or Se vapor ambient. However, it was hardly reported that the MoSe2 layer formed after the CIGS formation by conventional three-stage co-evaporation process. Indeed, it is difficult to maintain sufficiently high Se overpressure within a evaporation chamber to form MoSe2 layer at Mo/CIGS interface after completing CIGS formation. Therefore, even though three-stage co-evaporation process has been employed to produce the best CIGS cell efficiency for last three decades, further improvement in cell efficiency has been limited by the absence of MoSe2 layer.

In this contribution, prior to CIGS formation we tried to form MoSe2 layer (~ 50 nm) intentionally by exposing glass/Mo substrates to Se flux at 550°C for 60min in molecular beam epitaxy reactor. Then, CIGS absorber was deposited by conventional three-stage process on the glass/Mo and glass/Mo/MoSe2 at the same conditions. In general, three-stage grown glass/Mo/CIGS sample shows strong (220) plane preferred crystal orientation, but glass/Mo/MoSe2/CIGS sample has relatively weak (220) plane preference. In addition, the addition of MoSe2 layer resulted in the improvement of maximum cell efficiency from 12.3% to 13.2%, primarily due to increased VOC (0.53-->0.57 V) and FF (~67 -->71%).
CP-32 The Effects of Surface Conditions of TIO2 Thin Film on the UV-Assisted Gas Sensing Response at Room Temperature
Ting Xie (University of Maryland, College Park, USA); Asha Rani (The George Washington University, USA); Baomei Wen, Audie Castillo, Brian Thomson, Ratan Debnath (N5 sensors, Inc., USA); Thomas Murphy, R.D. Gomez (University of Maryland, College Park, USA); Abhishek Motayed (N5 sensors, Inc., USA)
Thin film oxides have attracted extensive attention due to their use in memory devices, UV detectors, gas sensors, and many others. The numerous applications benefit from the unique physical, optical, and chemical properties of the thin film oxides. These properties are known to be strongly dependent on the surface conditions of the thin films. However, it is not yet clear how surface properties of the thin film gas sensor affect its analyte sensing response. Here, we report the influence of surface carbon contamination and roughness on the NO2 sensing properties of TiO2 thin film sensors. The TiO2 thin films were prepared by rf-sputtering. The surface of the films were intentionally contaminated and damaged with organic polymers (photolithography resist) and microwave plasma, respectively. The surface chemistry of the films was assessed by high resolution X-ray photoelectron spectroscopy, and atomic force microscopy was exploited to obtain the morphology of the fabricated sensors. Our results indicate that the carbon residue and surface roughness diminishes the NO2 response and recovery rate of the TiO2 based sensor.
CP-33 Fabrication and Study the Performance of Solar Cell made from Newnanostructure Phthalocyanine Complex Thin Film
Asmaa Hendi (King Abdulaziz University, Saudi Arabia)
Nanocrystalline thin film of 2,3,9,10,16,17,23,24-octa(n-hexyl) phthalocyaninatoruthenium(II), [(nhexyl) 8PcRu] deposited under high vacuum by thermal evaporation technique. The surface morphology of [(n-hexyl)8PcRu] thin film was measured using transmission electron microscopy (TEM) which showed nano-rod structures. The current–voltage (I–V) and capacitance–voltage (C–V) measurements of [(n-hexyl)8PcRu] onto p-Si substrate were studied. Dark current voltage (I–V) measurement was investigated at different temperatures ranging from 308 to 378 K indicates two conduction mechanisms: the first at lower forward voltages thermionic emission and second at higher forward voltages space charge limited currents (SCLC) with a single trap level. The ideality factor, n, series resistance RS, shunt resistance, RSh, and barrier height, Fb, were determined. The study of reverse voltage bias was interpreted in terms of generation-recombination. Abrupt nature was observed from dependence of capacitance–voltage for the device. Photovoltaic behavior was exhibited with power conversion efficiency h of 2.1%.
CP-34 Mechanical and Tribological Properties of CdO-TiO2 Films Obtained by Sol-gel Technique
Francisco Flores-Ruiz (CINVESTAV-Unidad Queretaro and CNyN-UNAM, Mexico); CarolinaJ. Diliegros-Godines (CINVESTAV-Unidad Queretaroand CNyN-UNAM, Mexico); F.A. Hernández-Garcia, Rebeca Castanedo-Pérez, Gerardo Torres-Delgado (CINVESTAV-Unidad Queretaro, Mexico); Esteban Broitman (Ningbo Institute of Material Technology & Engineering, CAS, Ningbo, China)

Mechanical and tribological properties of thin films from the mixed system CdO-TiO2 are reported. The films were deposited on glass substrates by sol–gel using a mixture of CdO and TiO2 solution precursors. Depending of the Ti/Cd ratio (0.20, 0.49, 0.65, 0.70 and 1), the films were constituted of CdO+CdTiO3 and CdTiO3 crystals. Films with Ti/Cd ratio of 0.65 and 0.70 have CdO+CdTiO3 phases and show wear rate of 740 and 1000 ×10-5 mm3 N-1m-1 that are higher than TiO2 films (30×10-5 mm3 N-1m-1). However, when the Ti/Cd=1 and the CdTiO3 phase is fully reached, the wear rate falls at 300×10-5 mm3 N-1m-1 which is much lower than the ones obtained for CdO films (5000×10-5 mm3 N-1m-1). Friction coefficient values are in the range 0.09-0.17 for all films. The reduced elastic modulus and the local plastic deformation, obtained by nanoindentation, are improved with the TiO2 addition . Photocatalytic activity tests in benzene gas degradation reported for these films showed that the films with Ti/Cd=0.65, 0.70 and 1 have a degradation rate that is 4-9 times higher than the values for TiO2 films. Because of their high photocatalytic activity and wear resistance, these films are good candidates for being applied as a photocatalytic material.

Time Period ThP Sessions | Topic C Sessions | Time Periods | Topics | ICMCTF2016 Schedule