ICMCTF2011 Session CP: Symposium C Poster Session

Previous work carried out by this group has shown that the thermal load experienced at the substrate is low when operating in HiPIMS mode, compared to DC and pulsed DC sputtering. It has also been seen that modifications are being made to thin film properties when produced by HiPIMS. AZO coatings have, therefore, been deposited under systematically varied conditions of pulse frequency and pulse width, selected to also vary the degree of ionisation in the plasma and incident at the substrate. The coatings were then characterised in terms of their structural, optical and electrical properties using SEM, EDX, XRD, optical spectroscopy and a Hall probe and the interrelationships between deposition parameters and film properties were explored. Further, different methods of reactive sputter control were tested in an effort to make HiPIMS sputtering onto polymeric web a reliable option for industrial processing.

The work presented here shows that TCO coatings with industrially relevant optical and electrical properties can be readily deposited onto thin, polymeric web. Although this is currently only on laboratory scale systems, transfer to a development-scale roll to roll system is in progress.

Here we report a systematic study of structural, optical, and magnetic measurements on Zn_0.9Cd_0.1S:yCo films in the concentration range of 0.005 y 0.05 M using pulsed laser deposition technique. Structure, composition analysis, and optical measurements revealed that Cobalt is incorporated into the lattice, as Co²⁺ substituting Zn²⁺ ions, forming a solid solution with cubic structure instead of Cobalt precipitates. Low temperature magnetization measurements reveal a paramagnetic behaviour. UV-Vis measurements showed a red shift with respect to undoped sample in the energy band gap with increasing Cobalt concentration. Photoluminescence measurements confirmed the substitution of Cobalt ions in the tetrahedral crystal field by showing the characteristic peaks.

This letter investigates the reliability issues of HfO₂/Ti_xN_1-x metal-oxide-semiconductor field effect transistor (MOSFETs) in terms of static and dynamic stress. The results indicate threshold voltage (V_T) instability under dynamic stress is more serious than that under static stress, owning to transient charge trapping within high-k dielectric. Using C-V techniques verified that electron trapping under dynamic stress was located in high-k dielectric near the source/drain (S/D) overlap region, rather than the overall dielectric. Furthermore, the V_T shift clearly increases with an increase in dynamic stress operation frequency. This phenomenon can be attributed to the fact that electrons injecting to the S/D overlap region have insufficient time to de-trap from high-k dielectric. We further investigated the impact of different Ti_xN_1-x composition of metal-gate electrode on charge trapping characteristics, and observed that V_T shift decreases significantly with an increase in the ratio of nitride. This is because the nitride atoms fill up oxygen vacancies and reduce the concentration of traps in high-k dielectric.

Transparent conduction oxides (TCOs) have high electrically conducting and high visible transmittance with widely used as transparent electrode for flat panel displays including liquid crystal display, organic light emitting diodes and plasma displays. The most important TCOs film in practical applications nowadays is Sn-doped In₂O₃ (ITO)⁽¹⁾. SnO₂ is an alternative potential candidate of ITO thin films due to its cheap and abundant raw material⁽²⁾. Thus, we focused on this material. SnO₂ is also a promising material for applications including gas sensors, photovoltaic solar energy conversion, and electrochromic devices. SnO₂ behaves like an n-type semiconductor with a wide energy gap (≈ 3.8eV) and has a tetragonal structure similar to the rutile structure.

In our previous paper⁽³⁾, FTO (0 ~ 5 mol%) films were grown on glass substrates by the spray pyrolysis method at 500˚C. The F-doping caused the resistivity to decrease and the carrier concentration to increase. The undoped and F-doped SnO₂ films were all n-types, which indicated that fluorine atoms can act as donor impurities. The lowest resistivity of 1.4 × 10^-3 Ωcm was obtained at a fluorine concentration of 4 mol%.

In the present study, transparent conducting F-doped SnO₂ films were successfully prepared on glass substrates by spray pyrolysis method in order to find out the effect of high F-doped concentration. The best electrical and optical properties, average transmittance of 82 % and resistivity of 3.9×10^-4 Ωcm, carrier concentration of 4.7×10²⁰ cm^-3, mobility of 34 cm²/Vs, were achieved with fluorine doing concentration of 17 mol% at substrate temperature of 500°C.

(1) H. Chen, X. Wang, Y. H. Yu, Z. L. Pei, X. D. Bai, C. Sun, R. F. Huang, L. S. Wen, Appl. Surf. Sci 158 (2000) 134.

(2) S. Takaki : Reports on Ashai Glass Co., Ltd. Research Center, 50 (2007) 105.

(3) M. Oshima, Y. Takemoto, K. Yoshino, Phys. Status Solid (C) 6 (2009) 1124.

Low-emissivity (low-e) coatings on glass are nowadays extensively used for energy saving applications in architectural windows and on solar thermal collectors. In this work we studied the feasibility of TiN-based layers, deposited by reactive magnetron sputtering, as cost-effective low-emissivity coatings. By changing the deposition parameters, different compositions of the films (measured by Glow Discharge Optical Emission-GDOES and Rutherford Backscattering Spectroscopy- RBS) and different textures and surface morphologies (X-Ray Diffraction-XRD and Scanning Electron Microscope-SEM) can be observed. These changes allow tuning the optical properties of the coatings, in particular, the transmittance (T) in the visible range, measured by Spectroscopic Ellipsometry (SE) and the emissivity (ε), measured both directly by an emissometer and indirectly by Fourier Transform Infrared Spectroscopy (FTIR). In order to improve the visible transmittance of TiN single layers we have proposed three strategies:

- Doping with aluminium, the T of the TiN films improves in a 15% but at the expenses of increasing their ε by a factor 1.3.

- Post-deposition annealing treatments up to 500^oC improve in a 10% the T at room temperature while keeping the ε.

- Multilayers structures (TiO₂/TiN/TiO₂) present the best results improving in a 30% the T of the TiN single layers while keeping the ε.

Hence, based on the control of the optical properties, and taking into account other properties such as thermal stability and long term durability, it is then possible to design selective coatings to be used in industrial solar thermal applications.

In this study, the circular polarization conversion reflectance is studied for [prism/SiO₂ helical thin film/air] configuration for the first time according to our knowledge. A circular polarization conversion reflectance from right(left)-circular polarization to left(right)-circular polarization was measured and calculated for a [prism/SiO₂ helical thin film/air] configuration under total internal reflection condition. It is found that the handedness of an incident circular-polarized light can be reversed with the highest circular polarization conversion reflectance of 92.2% at an incidence angle of 57.8±0.1°. Principal refractive indices of the helical film were derived by fitting the measured circular polarization conversion reflectance to the calculated one.

In this study, inorganic-solid-state electrolyte tantalum oxide thin films were deposited by D.C. reactive magnetron sputtering to improve the leakage and deterioration of the traditional liquid electrolyte of electrochromic device. The parameter of O₂ atmospheres (the flow rate range : 1~20sccm) and powers (35~100W) were conducted to prepared the tantalum oxide films with various compositions, microstructures, optical properties and electrochromic properties. The results indicated that tantalum oxide thin films were amorphous, near stoichiometric, porous with loose fibrous structure, and highly transparent in nature. As the oxygen flow rate and power increased, the refractive index increased however the current density and optical transmission change as the film decreased. At the oxygen flow rate of 3sccm and 50W, the transmission change between colored and bleached states at a wavelength of 550nm was 56.7%. The all solid electrochromic device was manufactured as the multilayer of Glass/ITO/WO₃/Ta₂O₅/NiO_x/ITO/Glass. The optical transmittance difference of the device increased as the applied voltage increase and the maximum change reached 66.5% in the applied voltage of ±5V.

Porous nanostructured SnO₂ films have been prepared using an ultrasonic spray pyrolysis technique in conjunction with cationic, anionic and non ionic surfactants namely CTAB (Cetyl trimethyl ammonium bromide), SDS (sodium dodecyl sulphate) and PEG (polyethylene glycol) respectively. The effect of surfactants on the structural, electrical, optical and gas sensing properties of SnO₂ films were investigated by using different techniques such as X-ray diffraction (XRD), Field emission scanning electroscope microscopy (FESEM), two probe technique and Photoluminiscence (PL) studies. The results reveal that the addition of surfactants in the precursor solutions leads to reduction in crystallite size with significant changes in porosity of SnO₂ films. PL studies of the films show emissions in the visible region which exhibit marked changes in the intensities upon variation of surfactants in the precursor solutions. The prepared films were tested for their sensing behaviour towards chlorine and the results reveal that the films prepared in conjunction with cationic surfactant CTAB exhibits a good sensing response towards chlorine at low operating temperatures.

Future active matrix display systems with enhanced performances are likely to be larger than they currently are. With the rapid progress in display technology, there has been increasing interest in developing oxide-based thin film transistors (TFTs) and many studies have been focused on variety oxide semiconductors that can be used as channel layers of the oxide-TFTs. Among those, sputtering-produced amorphous indium-zinc-oxide (a-IZO) thin films exhibit high electron mobility even when it is deposited at room temperature. Also, their conductivity can be controlled by varying the oxygen partial pressure, the sputter power, and the composition of target material. It is possible that a-IZO thin films are used both as a channel layer and as source/drain (S/D) layers of TFTs. To use the a-IZO thin film as a channel layer, it is often deposited in oxygen ambient to reduce the carrier concentration. This manner, however, may significantly increase the electrical resistivity of a-IZO films, leading to the deterioration of a-IZO TFT’s performance.

In this study, we suggest a novel two-step deposition process, by which a-IZO TFTs with excellent on/off current ratios can be achieved without deteriorating their TFT performance. The a-IZO TFTs were fabricated with a bottom gate structure. An n-type Si (100) wafer with a low resistance (below 0.002 Ωcm) was used as a gate, and a gate oxide layer (300 nm) was formed by thermally oxidizing the Si substrate . Then, a-IZO channel layer was deposited on the gate oxide layer via the RF sputtering method by following the two-step deposition procedure. The 1^st step deposition was done at a relatively low oxygen partial pressure (i.e., O₂/Ar < 5 %) formed to get a higher mobility. The 2^nd step deposition was accompanied without stopping the vacuum, only by increasing the oxygen partial pressure (i.e., O₂/Ar > 10 %) to maintain low off-current levels. The source/drain contact area was defined by photolithography and the source/drain regions uncovered by photoresists were plasma-treated to reduce the contact resistances. The a-IZO films used for the source/drain contacts were deposited via the same RF sputtering system under a pure Ar environment. For all the deposited IZO films, the electrical, optical, and chemical analyses were carried out and the results were characterized in terms of various O₂/Ar ratios and plasma treatment conditions. The device characteristics of the a-IZO TFTs fabricated by the proposed two-step method were compared those fabricated by the conventional single deposition process. The results showed that the on/off current ratio was significantly improved by the proposed two-step process.

Thin film transistors (TFTs) made by an amorphous Si (a-Si) have been important elements in the flat-panel display. However, a-Si TFTs have critical problems such as light sensitivity and low mobility (< 1 cm²/V×s). To resolve these problems, use of oxide semiconducting materials as a channel layer for TFT has recently been introduced. The channel materials of most oxide TFTs are comprised of zinc oxide (ZnO) and various compounds based on ZnO. Among those, ZnO is one of the most promising candidates for the transparent TFT applications since it has good crystallinity even when prepared at low temperature and it also has a widely range conductivity from metallic to insulating. When ZnO films are exposed to air, however, they often show unstable electrical properties (e.g., their electrical resistivities significantly increase), resulting in the degradation of the ZnO-based TFT’s device performance. It was also recently observed from our experiment and other group’s works that the electrical properties of hydrogen-incorporated ZnO films showed to be less sensitive to the air exposure. This was believed to be due to the role of hydrogen atoms that limited the adsorption of oxygen at the ZnO surface. However, this issue has scarcely been studied.

Chalcopyrite Cu(InGa)Se₂-based materials have demonstrated the potential of high efficiency thin film solar cells, yielding around 20% cell efficiency. Conventional method to fabricate CIGS absorber follows either elemental coevaporation of individual elements (i.e., Cu, In, Ga and Se) or reactive annealing of metallic precursors (i.e., Cu-Ga-In). The reactive annealing of metallic Cu-Ga-In precursors under Se or H₂Se is a likely method of producing effectively large area Cu(InGa)Se₂. However, Ga accumulation near the Mo side of substrate/Mo/CIGS structure is often observed during the selenization of Cu-Ga-In precursors yielding phase-separated CuInSe₂ and CuGaSe₂ which subsequently lead to lower open-circuit voltages.

In this contribution, rapid thermal process (RTP) using stacked binary (metal-Se) precursors, e.g., glass/Mo/In_xSe_y/Cu_xSe, was explored to reduce the reaction time of CuInSe₂ formation drastically, while maintaining compositional depth uniformity. Various binary stacked precursors, including In₂Se₃/CuSe and InSe/CuSe, were prepared onto Mo-coated glass substrates. The reactive annealing of metal precursors was performed in a rapid thermal process system consisting of a quartz tube reactor with an inner diameter of 62 mm, quartz sample tray and infrared (IR) heater under a Se atmosphere. The quartz sample tray held up to six 1 cm x 1 cm samples. The IR heater ramped temperature rapidly, requiring only 1 min to reach 1,000˚C from room temperature. At a fixed annealing temperature of 550˚C, it was confirmed that reaction time of 2 min was sufficient enough to form CuInSe₂ by completely consuming binary reactants. The longer reaction time of 5~10 min caused the formation of MoSe₂ at CuInSe₂/Mo interface.

Precursor and CuInSe₂ structures were characterized by x-ray diffraction (XRD) and scanning electron microscope (SEM). Bulk composition and compositional depth profiles of the films were measured by inductively coupled plasma optical emission spectroscopy (ICP-OES) and secondary ion mass spectrometry (SIMS), respectively.

In engineering design, care is taken to avoid dissimilar metal contact that cause galvanic corrosion in aqueous environments. Engineers and designers often use coatings to minimize the effect of galvanic attack. Cadmium-based coatings provide excellent barrier and sacrificial corrosion protection on steel, as well as desirable physical and mechanical properties of self-healing and anti-seizure; however, such coatings are effectively banned from many applications due to the toxic nature of both coating and application technique. Ever more stringent environmental regulations lead to an increasing need to develop coatings with equally good corrosion resistant behaviour to that of cadmium, which are also environmentally benign. Aluminium-based coatings can exhibit corrosion potentials similar to cadmium, such that (if the coating is damaged) aluminium will preferentially corrode instead of the exposed substrate. Traditional corrosion evaluation techniques (such as salt spray testing) are useful in screening coating behaviour (ie. acceptable performance or not) but reveal little of the underlying complex electrochemical phenomena that lead to the observed behaviour. Therefore, this study examines the electrochemical behaviour of a selection of commercially available Al based coatings on steel in 0.6 M NaCl solution, to provide in-depth information on the corrosion processes involved, and their evolution with time.

The corrosion performance of the coatings was assessed by various electrochemical techniques. Open-circuit potential (OCP) stability measurements were carried out for a period of 2 hours, against the resting potential of each coating in 0.6 M NaCl solution. Potentiodynamic polarization scanning was performed at a rate of 1.667mV/s starting at – 0.2V vs. OCP and ending at 0V vs. SCE. In the galvanic corrosion tests, uncoated steel was the working electrode while the coated steel substrates were used as the counter electrode, the reference being a saturated calomel electrode (SCE). The data acquisition rate was 0.1 points/second for a duration of 2 hours at 0V vs. OCP. SEM images and EDX analysis were also used to characterise the morphology, elemental composition and the physical degradation of the coatings. Results obtained indicate that thermally sprayed Al coatings give high corrosion current densities with polarisation behaviour similar to that of cadmium. Electroplated and IVD aluminium coatings showed passivation and periodic breakdown and regrowth of the passive film over a range of applied potentials, while coatings containing aluminium particles in a chromate/phosphate inorganic binder give OCP values very close to that of steel.

Zinc Oxide is a material of technological importance for its practical and potential applications for short wavelength optoelectronic devices and transparent conductive oxide films, such as in UV-lasers, blue to UV light-emitting diodes and solar cells electrodes. This oxide is also used in glass stacking as a UV spectrum filter and can provide other promising technological applications thanks to its adjusting photoluminescence properties. The advantage of the magnetron sputtering technique is the achievement of polycrystalline ZnO films deposition on large flat glass area without intentional substrate heating. However, it results in residual stresses which can be detrimental when occurrence of spontaneous delamination, or under scratch during processing or in service. The control of their mechanical reliability can then be achieved by an in depth comprehension of the residual stresses build up or relaxation mechanisms occurring in the films in relation with the material structure.

Residual stress evolution in sputtered ZnO films has been studied in-situ in a furnace by synchrotron X-ray diffraction. The films sputter deposited on (001) Si substrates were thermally cycled from 25°C up to 700°C and down to 25°C . X-ray diffraction 2D patterns were captured continuously during the heating, plateau and cooling ramps. The corrections carried out for compensating the furnace drift are presented. The obtained stress state is observed to change from compressive to tensile upon cooling. Stress amplitudes increase up to 370°C and, then stress relaxation is detected. The overall behaviour is discussed in terms of structure changes induced during the heat treatment. This work is done in the framework of an ANR project named Merethif.

Nickel (Ni) films are widely used in electrochemistry, microelectronics, energy and nanotechnology. In integrated optics, the nanometric Ni films are used as a source for doping LiNbO₃ substrate and optical waveguide fabrication by thermal diffusion. Because effective refractive indices of the waveguide modes are strongly dependent on the optical profiles in doped layer, precise control of Ni film thickness (h) is needed in the range h~10-50 nm. Ellipsometry can be successfully applied for nondestructive determination of the thickness of a dielectric and semi-transparent metal film when optical constants of the material are known. Regrettably, noticeable scattering was found for optical constants reported earlier in literature for Ni films and crystals. As it seems, this scattering appeared due to different film quality or crystal surface preparation. The focus of the present work is centered on Ni film fabrication by thermal evaporation, evaluation of their optical parameters with spectroscopic ellipsometry, and compares the results with those determined for Ni single crystal . Nickel single crystals (99,995%) were grown by directional solidification from machined polycrystalline blanks in graphite mold. Laue X-ray back reflection method was used for crystal orientation. Specimens were sliced from the single crystal by means of an acid saw. The specimen with the smoothest polished surface was studied by spectroscopic ellipsometry method. Nickel films were fabricated by thermal evaporation method in vacuum below 10^-5 Torr. The substrate temperature was T=100 °C. For precise determination of optical parameters, thick Ni film (h~100 nm by as determined from optical interferometry) was prepared on silica substrate. To increase the metal adhesion, the substrate was subjected to RCA chemical cleaning just before insertion into vacuum chamber. Structural parameters of Ni films were studied with reflection high-energy electron diffraction (RHEED). Thermally evaporated Ni films are polycrystalline. Spectral dependencies of refractive index n(l) and extinction coefficient k(l) were determined with the help of spectroscopic ellipsometry in the spectral range, l~250-1030 nm. The n and k increase continuously with l. Such a behavior is typical for refractive metals. The dependencies k(l) determined for the film and crystal surface are very close. The curves n(l), however, are close in the shape but the refractive index of Ni film is slightly higher than that determined for single crystal. This refractive index gap ~0.1 between the curves may be appeared due to different surface state of Ni film compared to single crystal (100) surface.

Langmuir-Blodgett self-assembled monolayers of the synthesized particles were deposited on 25-100 cm2–substrates of silicon and glass. Depending on the size distribution, the particle monolayers were characterized by either hexagonal or disordered compact structures.

Morphological properties (particle roughness, shape, surface pattern) were characterized by Atomic Force Microscopy and Scanning Electron Microscopy. Transmittance spectra and ellipsometry measurements provided the optical properties of the colloidal films, which were connected to the degree of their structural order and compactness. The effects of film characteristics on wettability were evaluated by contact angle measurements. Colloidal films can find application in photonics but also as smart surfaces with controllable photo-switched wettability and photocatalytic properties. They are also promising for applications in bioengineering and photovoltaic cells.

Diamond-Like Carbon (DLC) has been long studied as a material for surface protection against wear and corrosion; in addition due to the vast range of its optical properties it has been applied in anti-scratch layers in photovoltaics and optical systems. The combination of its exceptional mechanical and optical properties with its reported high thermal conductivity makes it a promising candidate for solar energy harvesting in solar trough collectors. However, its optical transparency is a major drawback for such applications, because the optical absorption spectrum of DLC does not cover the whole solar spectrum.

In this work we incorporated metal nanoparticles into DLC in order to extend its optical absorption into the visible spectral range. We have grown a variety of DLC:Me (Me=Ag, Cu, Ti, Zr, Ni) nanocomposites of varying metal and sp³ volume fractions by pulsed laser deposition. A detailed study of their optical properties has been performed using optical reflectance and transmittance measurements as well as spectroscopic ellipsometry. The optical properties of the DLC films have been correlated with their structural features such as the metal and sp³ volume fractions (measured by in-situ Auger electron spectroscopy) and density (measured by in-situ electron energy loss spectroscopy). In addition, their mechanical performance and adhesion to various materials used for solar trough collectors have been evaluated by nanoindendation and scratch testing. Finally, the various DLC:Me films have been thermally (in a vacuum furnace and in ambient) and optically (using a solar simulator) annealed and the changes in their integrity and optical performance have been evaluated, in an effort to identify their potential for realistic applications in solar harvesting.

The reactive annealing of metallic Cu-Ga-In precursors under Se or H₂Se is a likely method of producing effectively large area Cu(InGa)Se₂. However, Ga accumulation near the Mo side of substrate/Mo/Cu(InGa)Se₂ structure is often observed during the selenization of Cu-Ga-In precursors yielding phase-separated CuInSe₂ and CuGaSe₂ which subsequently lead to lower open-circuit voltages. Cu(InGa)Se₂ films formed by selenization of metal precursors are readily delaminated from Mo layers during CdS chemical bath deposition due to their poor adhesion. It has been suggested that a MoSe₂ layer may affect the adhesion at the interface of Cu(InGa)Se₂ and Mo. In particular, a MoSe₂ layer oriented parallel to the surface of the Mo layer shows poor adhesion because hexagonal MoSe₂ compounds are stacked by weak Van der Waals interactions.

In our research group, the reactive annealing of metal precursors was performed in a rapid thermal process (RTP) system consisting of a quartz tube reactor with an inner diameter of 62 mm, quartz sample tray and infrared (IR) heater. The quartz sample tray held up to six 1 cm ´ 1 cm samples. The IR heater ramped temperature rapidly, requiring only 1 min to reach 1,000°C from room temperature. CuGa-In precursors were prepared on Mo-coated thin sodium-free Corning 7059 glass (SFG) of 0.7mm thickness by sequentially or simultaneously sputtering CuGa alloy with 24wt% Ga and elemental In targets. Total thicknesses of precursors were intended to be 600 ~ 700 nm. The atomic compositions of the precursors were confirmed to be Cu/(In+Ga) = 0.9 ~ 1.0 and Ga/(In+Ga) ~ 0.3.

In this paper, the effects of annealing temperature and ramp rate on the properties of Cu(InGa)Se₂ fims deposited by rapid thermal annealing were systematically investigated, with particular attention paid to the formation of MoSe₂ and compositional depth profiles.

The effect of annealing atmosphere on electrical metastability of a-InGaZnO TFT is investigated. The generation of oxygen vacancies by the annealing in a vacuum led to an increased I_off and large V_th shifts, while N₂ and O₂ ambience effectively improve the device performance. A physical mechanism is also reasonably proposed. Amorphous transparent conductive oxide (a-TCO) has attracted lots of attention for its superior electrical performance and insensitivity characteristics to visible light. One of the most popular candidates of a-TCO material nowadays is amorphous indium gallium Zinc Oxide (a-IGZO). However, some fundamental transport mechanisms still need to be clarified, otherwise it will limit the technology development for realistic application. In addition, previous studies reported thermal annealing process was able to critically dominate the electrical performance of a-IGZO TFT, but the process factors in the annealing process have not be specified completely. In this study, the effect of annealing atmosphere (pure N₂, pure O₂, and vacuum) will be studied to explore the optimum annealing conditions for the sputter-deposited a-IGZO TFT. Electrical reliability also will be investigated further by analyzing electrical behavior after gate bias stress in the ambient air and a vacuum. In summary, experimental results indicated the effects of annealing atmosphere on electrical metastability of the a-IGZO TFT under gate bias stresses with different voltage polarities. Annealing temperature would improve the front channel properties while the annealing atmosphere would modify vacancies at the back channel. For the O₂-annealed and N₂-annealled a-IGZO TFT, the magnitude of the V_th variation was similar in atmosphere and vacuum during positive gate bias stress, because of the lack of oxygen vacancy in backchannel. However, H₂O would stay on the surface of a-IGZO and resulted in different V_th variations in atmosphere or vacuum during negative gate bias stress.

Zirconium oxide (ZrO₂) is an important material with a potential for a wide range of technological applications. The outstanding chemical stability, electrical and mechanical properties, high dielectric constant, and wide band gap of ZrO₂ makes it suitable for several industrial applications in the field of optics, electronics, magneto-electronics, and optoelectronics. ZrO₂ is frequently used as a high refractive index material in multilayer optical coatings in high power laser systems. ZrO₂ is employed in superplastic structural ceramics that demonstrate excellent strength and fracture toughness. ZrO₂ has been considered as a promising dielectric to replace SiO₂ in advanced metal oxide semiconductor (MOS) devices in gate stack. However, it is well known that the electrical and optical properties of ZrO₂ thin films are highly dependent on the film-substrate interface structure, morphology, and chemistry, which are in turn controlled by the film-fabrication technique, growth conditions, and post-deposition processes.

The objective of the present work is to better understand the growth and local structure, interface structure, and chemical reactions at the ZrO₂-Si interface using electron microscopy. The ultimate goal is to minimize the interface diffusion using the surface nitridation approach. In the present work, ZrO₂ thin films have been prepared by the radio-frequency magnetron sputter-deposition onto Si(100) substrates as a function of growth temperature (T_s) varied in a wide range of 30-500^oC. The growth behavior, surface structure and morphological features, interface structure, and chemical analysis of surfaces and interfaces have been examined by the high-resolution transmission electron microscopy (HRTEM) and high-resolution scanning electron microscopy (HR-SEM). HRTEM and HRSEM are considered to be the best capabilities to examine the ultra-microstructure of the ZrO₂-Si interface. The results indicate that the effect of T_s on the surface structure, interface layers and morphology of ZrO2 films is significant. ZrO₂ films grown at 30^oC are amorphous without IL formation. An increase in T_s results in the formation of nanocrystalline ZrO₂ films. A significant amount of interface mixing occurs at higher temperatures (T_s=500^oC) where the clear distinction between ZrO₂ and Si is not possible. The grain sizes determined are in the range 5-40 nm, where the temperature-dependence is clear. Efforts are made to explain the quantitative information, obtained based on the electron microscopy results, making use of the existing models to account for growth behavior and interface structure.

This investigation reports the preparation and characterization of the conductive polymer regular poly(3-hexylthiophene) (rrP3HT) and copper indium diselenide (CuInSe₂) and titania (TiO₂) nanocrystals and their application in hybrid solar cells. Quantitative area calculation of the ¹H NMR spectra showed that the regularity of the prepared rrP3HT was 93.82%. The rrP3HT was further blended with different contents of CuInSe₂ and TiO₂ nanoparticles and spin cast onto the ITO glass. The prepared nanocomposites were characterized by SEM, AFM, TEM, UV-vis, FTIR, PL, and XRD analysis. TEM and XRD analysis showed that the prepared CuInSe₂ and TiO₂ nanoparticles had a high degree of crystallinity. UV-vis and PL spectra of the prepared P3HT:CuInSe₂:TiO₂ nanocomposites indicated that the absorption and emission spectra increased and decreased with increasing amount of titania, respectively. SEM and AFM images showed that no phase separation could be observation for the prepared P3HT:CuInSe₂:TiO₂ films. Solar cells with a device structure of ITO/NiO/P3HT:CuInSe₂:TiO₂/Ca/Al were then produced by evaporation of NiO ,Ca and Al as the back contact. Analysis of solar cells showed that the incident photon to converted electron efficiency (IPCE) and energy conversion efficiency (h) increased with the increase in CuInSe₂ content. The maximum value of IPCE and h could be obtained as the TiO₂ content was 25wt%.

This paper describes the influence of the type of magnetron sputtering deposition (MSDs) on the characteristics of impurity-doped ZnO thin films for applications as transparent electrodes in thin-film solar cells. An r.f. power-superimposed d.c magnetron sputtering deposition (r.f.+d.c.-MSD) that produced a decrease in deposition damage and obtainable resistivity as well as an increase of deposition rate is demonstrated. Transparent conducting Al- and Ga-doped ZnO (AZO and GZO) thin films were deposited using a magnetron sputtering apparatus with an oxide target, and both an d.c. and an r.f. (13.56 MHz) power supply was applied either separately or in combination. The oxide targets used were commercially available high-density-sintered rectangular targets (127 mm×275 mm). A substrate of OA-10 glass (Nippon Electric Glass Co., Ltd.) with an area of 200 mm×200 mm was placed parallel to the target surface at a substrate-target distance of 90 mm. Sputtering depositions were carried out at a deposition temperature of 200^oC in a pure Ar gas atmosphere at 0.2 Pa. For transparent conducting AZO and GZO thin films prepared by various types of MSDs, the surface morphology and the crystallinity obtained by supplying r.f. power such as in r.f.-MSD and r.f.+d.c.-MSD outperformed those obtained with d.c.-MSD. A higher deposition rate and lower resistivity exhibited in the AZO and GZO thin films prepared by r.f.+d.c.-MSD were obtained in comparison with those found with r.f.-MSD and d.c.-MSD, respectively. To evaluate the light scattering characteristics suitable for applications in thin-film solar cells, surface texturing of the samples was carried out by wet-chemical etching in a 0.5% HCl solution. Subsequently, surface morphology observation and measurements of the optical transmittance and the diffusive component of the surface-textured AZO and GZO thin films were also performed. The high transmittance and high haze properties obtained by supplying such r.f. power as in r.f.-MSD and r.f.+d.c.-MSD outperformed those obtained with d.c.-MSD. The influence of the type of MSD described above may be attributable to decreases of the amount and activity of oxygen reaching the substrate surface; a lower electric field reflects lower sputter voltage in r.f.-MSD and r.f.+d.c.-MSD. Thus, the demonstrated low-damage and high-rate preparation of impurity-doped ZnO transparent electrodes on low temperature substrates by r.f.+d.c.-MSD are suitable for solar cell applications.

This paper describes the PL and EL characteristics of newly developed rare earth (RE)-activated BaLa₂O₄ oxide phosphor thin films with or without the co-doping of Bi and prepared by magnetron sputtering depositions. BaLa₂O₄ phosphor thin films were prepared on thick BaTiO₃ ceramic sheets by either a conventional or a combinatorial radio frequency (r.f.) magnetron sputtering (rf-MS) deposition method using a powder target, which was a mixture of oxide powders. In combinatorial rf-MS depositions, BaLa₂O₄:Bi,RE phosphor thin films with either Bi or RE content that varied across the substrate surface were deposited using a powder target divided into two parts. The sputter depositions were carried out under the following conditions: atmosphere, pure Ar or Ar+H₂; pressure, 6 Pa; r.f. power, 100 W; and substrate temperature, 350^oC. The thickness of all deposited phosphor thin films was approximately 1.5 μm. After the depositions, postannealing was carried out in a pure Ar or a reducing gas atmosphere at a temperature up to 1100^oC. TFEL devices were fabricated by depositing an Al-doped ZnO thin-film transparent electrode and an Al thin-film back electrode on the phosphor thin-film emitting layer and the BaTiO₃ ceramic sheet, respectively. As an example, multicolor PL emissions were always observed from BaLa₂O₄:Bi,Eu phosphor thin films prepared with appropriate Bi and Eu contents and postannealed at 1000-1100^oC. However, the spectral shape of the PL emissions observed from the postannealed BaLa₂O₄:Bi,Eu phosphor thin films were considerably affected by the postannealed atmosphere. In addition, multicolor EL emissions were obtained in TFEL devices fabricated using postannealed BaLa₂O₄:Bi,Eu thin films prepared by varying either the Bi or Eu content. The observed blue emission band peaking at a wavelength around 420 and 450 nm may reflect the transition in Eu²⁺ and the 6s²-6s¹6p¹ transition in Bi³⁺, respectively. The multiple sharp emission peaks involving red emissions peaking around 610 and 620 nm are assigned the transition in Eu³⁺. It can be concluded that multicolor PL and EL emissions, which were observed from BaLa₂O₄:Bi,RE phosphor thin films prepared by varying either Bi or RE content, allow the control of emission color over a wide range. In addition, BaLa₂O₄ is very promising as new host materials for oxide phosphor applications.

Zinc oxide (ZnO) has attracted intensive research effort in recent years, due to its unique properties and versatile applications. Besides, ZnO is naturally of n-type conduction due to a large number of native defects. Recently, the researches of ZnO electrical conductivities are focused on the synthesis of p-type ZnO using various techniques and dopants. Recent work on the conservation of surface plasmon and light through period metal arrays has elucidated the propagation of surface plasmon resonance (SPR) behavior. In this paper, we discuss the SPR dispersion relations with various Al cylindrical micropillars by measuring the surface charge displacements. Optical characterization of exciton coupled with SPR for indium-doped ZnO nanowires with Al cylindrical micropillars has been also investigated.