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Dry etching of InGaZnO (IGZO) thin films was performed in a capacitively coupled plasma-reactive ion etching (CCP-RIE) mode using hydrochloride (HCl) and argon (Ar) gases. Dry-etching characteristics and surface properties of IGZO films were then investigated according to gas mixture ratio, radio frequency power, and chamber working pressure. With an optimized ratio of HCl : Ar at 20 : 20 SCCM, the IGZO film showed good etch characteristics with a moderate etch rate of 6.0 nm/min and a low roughness of 0.19 nm. During the etching process of IGZO thin films, nonvolatile by-products such as GaClx, InClx, and ZnClx generated on the surface could be effectively removed by physical bombardment with Ar+ ions. As a result, we successfully conducted dry etching of IGZO thin films in the CCP-RIE system under HCl-Ar gas conditions, which demonstrated dry etching on IGZO without needing a fluorine-based etching gas. [ABSTRACT FROM AUTHOR]

Sequential infiltration synthesis (SIS) is an emerging vapor-phase synthetic route for the preparation of organic–inorganic composites. Previously, we investigated the potential of polyaniline (PANI)-InOx composite thin films prepared using SIS for application in electrochemical energy storage. In this study, we investigated the effects of the number of InOx SIS cycles on the chemical and electrochemical properties of PANI-InOx thin films via combined characterization using X-ray photoelectron spectroscopy, ultraviolet–visible spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and cyclic voltammetry. The area-specific capacitance values of PANI-InOx samples prepared with 10, 20, 50, and 100 SIS cycles were 1.1, 0.8, 1.4, and 0.96 mF/cm², respectively. Our result shows that the formation of an enlarged PANI-InOx mixed region directly exposed to the electrolyte is key to enhancing the pseudocapacitive properties of the composite films. [ABSTRACT FROM AUTHOR]

This study identified time-varying harmonic characteristics in a high-density plasma (HDP) chemical vapor deposition (CVD) chamber by depositing low-k oxide (SiOF). The characteristics of harmonics are caused by the nonlinear Lorentz force and the nonlinear nature of the sheath. In this study, a noninvasive directional coupler was used to collect harmonic power in the forward and reverse directions, which were low frequency (LF) and high bias radio frequency (RF). The intensity of the 2nd and 3rd harmonics responded to the LF power, pressure, and gas flow rate introduced for plasma generation. Meanwhile, the intensity of the 6th harmonic responded to the oxygen fraction in the transition step. The intensity of the 7th (forward) and 10th (in reverse) harmonic of the bias RF power depended on the underlying layers (silicon rich oxide (SRO) and undoped silicate glass (USG)) and the deposition of the SiOF layer. In particular, the 10th (reverse) harmonic of the bias RF power was identified using electrodynamics in a double capacitor model of the plasma sheath and the deposited dielectric material. The plasma-induced electronic charging effect on the deposited film resulted in the time-varying characteristic of the 10th harmonic (in reverse) of the bias RF power. The wafer-to-wafer consistency and stability of the time-varying characteristic were investigated. The findings of this study can be applied to in situ diagnosis of SiOF thin film deposition and optimization of the deposition process. [ABSTRACT FROM AUTHOR]

In this study, we assessed the physical and chemical properties of HfO2 thin films deposited by plasma-enhanced atomic layer deposition (PEALD). We confirmed the self-limiting nature of the surface reactions involved in the HfO2 thin film's growth by tracing the changes in the growth rate and refractive index with respect to the different dose times of the Hf precursor and O2 plasma. The PEALD conditions were optimized with consideration of the lowest surface roughness of the films, which was measured by atomic force microscopy (AFM). High-resolution X-ray photoelectron spectroscopy (XPS) was utilized to characterize the chemical compositions, and the local chemical environments of the HfO2 thin films were characterized based on their surface roughness and chemical compositions. The surface roughness and chemical bonding states were significantly influenced by the flow rate and plasma power of the O2 plasma. We also examined the uniformity of the films on an 8″ Si wafer and analyzed the step coverage on a trench structure of 1:13 aspect ratio. In addition, the crystallinity and crystalline phases of the thin films prepared under different annealing conditions and underlying layers were analyzed. [ABSTRACT FROM AUTHOR]

Miniaturized and "smart" sensors are required for research in biology, physiology, and biomechanics, and they have extremely important clinical applications for diagnostics and minimally invasive surgery. Fiber optic sensors have been proven to provide advantages compared to conventional sensors and high potential for biomechanical and biomedical applications. They are small, easy to operate, minimally invasive with low risk, more accurate, and inexpensive. This paper reports the design and modeling of a fiber optic force sensor that is capable of measuring compliance for a contact force of up to 1 N. The main objective of this study is to design and model a fiber optic sensor capable of measuring the total force applied on an object. A polydimethylsiloxane (PDMS) elastomer film with a thickness of 1.2 mm is placed between an optical fiber tip and an object, and it is used for measuring the force applied on a rigid element. The compliance of the fiber optic force sensor is measured by recording the response of PDMS elastomer films under different load conditions. We use finite element modeling results as a basis for comparing experimental data. The agreement between theoretical predictions and experimental data is reasonable and within an acceptable range. [ABSTRACT FROM AUTHOR]

Deals with a study which investigated stress-temperature behaviors of RuO[sub2] thin films on (100) silicon by measuring the deflection of film-coated substrates in situ during thermal cycling. Experimental methods; Results and discussion; Conclusion.

Presents a study which investigated the thickness dependence of the preferred orientation of Mn-Zn ferrite thin films deposited by ion-beam sputtering. Theories of preferred orientation; Examination of the thickness dependence of magnetic properties of the ferrite films; Importance preferred orientation of thin films.

Describes a technique for the formation of titanium (Ti)-nitrogen (N) film with large grain size from TiN layer deposited by sputtering in argon and nitrogen. Overview of the film properties and electromigration; Epitaxial continuity at the aluminum/TiN interface; Structural properties of the TiN mutilayered aluminum interconnection and its EM characteristics.

In-Ga-Sn-O (IGTO) thin-film transistors (TFTs) were fabricated with Al 2 O 3 gate insulators by plasma-enhanced atomic layer deposition (PEALD) at a temperature of 150 °C. Electrical performances of IGTO TFTs were significantly affected by plasma conditions when Al 2 O 3 was deposited on IGTO thin films by PEALD. Analyses of X-ray photoemission spectroscopy revealed that excessive oxygen species activated at high plasma power above 150 W were chemisorbed to IGTO films to create excess oxygen bonds such as oxygen interstitials (O i). Distributions of density of states in IGTO bandgap extracted by photonic capacitance-voltage measurement matched well with positive bias stress (PBS) instability of TFTs. Split-oxygen interstitials [O i (split)] first created on IGTO by oxygen plasma might migrate to the octahedral site by a constant high gate bias to form octahedral-oxygen interstitials [O i 2- (oct)] by capturing electrons under PBS and reside deep states. Significant changes of subthreshold slope in I-V characteristics during the recovery time after removing PBS indicated that these octahedral-oxygen interstitials such as O i (oct) and O i 2- (oct) obviously originated from O i (split) initially formed by plasma and that O i (oct) defects created by a relaxation process acted as a neutral acceptor-like state above Fermi level and deteriorated electrical properties of IGTO TFT. [Display omitted] • Electrical properties of InGaSnO (IGTO) thin-film transistors (TFTs) with Al 2 O 3 by atomic layer deposition (ALD) with different plasma power. • Analysis of defect states in IGTO films and IGTO-Al 2 O 3 interfaces according to different ALD plasma power. • Extraction of density of state of IGTO from photo-responsive capacitance-voltage measurement. • Interpretation of degradation mechanism for electrical characteristics and stability of IGTO TFT by oxygen plasma. [ABSTRACT FROM AUTHOR]

Highly efficient red-green-blue (RGB) tricolor luminescence switching was demonstrated in a bicomponent solid film consisting of (2 Z,2′ Z)-2,2′-(1,4-phenylene)bis(3-(4-butoxyphenyl)acrylonitrile) (DBDCS) and (2 Z,2′ Z)-3,3′-(2,5-bis(6-(9 H-carbazol-9-yl)hexyloxy)-1,4-phenylene)bis(2-(3,5-bis(trifluoromethyl)phenyl)acrylonitrile) ( m-BHCDCS). Reversible RGB luminescence switching with a high ratiometric color contrast ( λem=594, 527, 458 nm for red, green, and blue, respectively) was realized by different external stimuli such as heat, solvent vapor exposure, and mechanical force. It was shown that Förster resonance energy transfer in the bicomponent mixture could be efficiently switched on and off through supramolecular control. [ABSTRACT FROM AUTHOR]

Abstract: We report on a solution processed reduced graphene oxide (rGO) thin films as anode buffer layer in organic solar cells. The spin-coated rGO, and zinc oxide (ZnO) thin films have been used to fabricate bulk heterojunction organic solar cells employing [poly({4,8-di(2-ethylhexyloxyl)benzo[1,2-b:4,5-b′]dithiophene}-2,6-diyl)-alt-({5-octythieno[3,4-c]pyrrole-4,6-dione}-1,3-diyl):fullerene (PBDTTPD:PCBM) blends as a photoactive layer. Atomic force microscopy, X-ray diffraction, UV–vis absorption spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and photovoltaic measurements were performed to investigate the morphology, materials of processed thin films, and device performance of the fabricated devices. The ZnO also plays an important role in blocking holes, collecting electrons and serves as conducting channels to the cathode top electrode. A short-circuit current density (J sc) and fill factor (FF), increase when the rGO was introduced, which directly contributed to the improved efficiency to 4.8%. [Copyright &y& Elsevier]

Purpose: The authors aim was to investigate the effects of using transmission and reflection scanning modes, the film orientation during scanning, and ambient room light on a dosimetry system based on the GafchromicTM EBT2 film model. Methods: For calibration, the films were cut to 3 × 3 cm2 and irradiated from 20 to 700 cGy at the depth of maximum dose using 6 and 10 MV photon beams in a 10 × 10 cm2 field size. Absolute dose calibration of the linear accelerator was done according to the TRS398 protocol. An FG65-G ionization chamber was used to monitor the dose while irradiating the films in solid water. The film pieces were scanned with an EPSON Expression 1680 Pro flatbed scanner in transmission and reflection modes. Authors investigated the effect of orientation on films and examined the optical properties of EBT2 film using an ellipsometer and an ultraviolet (UV)/visible spectrometer to explain the dosimetric dependence of the film on orientation during the scanning process. To investigate the effect of ambient room light, films were preirradiated in 6 and 10 MV photon beams with intensity-modulated radiotherapy (IMRT) quality assurance (QA) plans, and then exposed to room light, either directly for 2 days in a workroom or for 2 months in a film box. Gamma index pass criteria of (3%, 3 mm) were used. Results: The dose response curves based on net optical density (NOD) indicated that the reflection scanning mode can provide a better dose sensitivity than the transmission scanning mode, whereas the standard deviation of the dose is greater in reflection mode than in transmission mode. When the film was rotated 90° from the portrait orientation, the average dose of the EBT2 film decreased by 11.5-19.6% in transmission mode and by 1.5-2.3% in reflection mode. Using an ellipsometer, variation of the refractive index of EBT2 film-the birefringence property-was found to be the largest between 45° (1.72 and 1.71) and 135° (1.8 and 1.77) for 300 and 800 cGy. Absorption spectra of EBT2 films measured with spectrometer were the function of film orientation. The readings in reflection scanning mode were more stable against room light than those in transmission scanning mode, although dose readings increased in both modes after the films were exposed to room light. Conclusions: The transmission scanning mode exhibited a strong dependence on film orientation during scanning and a change in optical density resulting from room light exposure, so a constant scanning orientation and minimal exposure to light can reduce uncertainty in the measured dose (23 ± 3%). The angular dependence was analyzed using Jones matrices and optical properties of EBT2 film were obtained using an ellipsometer and an UV/visible spectrometer. The reflection scanning mode has relatively good stability with respect to room light and film orientation on a scanner, although the large standard deviation of dose is a disadvantage in measurements of absolute dose. Reflection scanning mode can offer a potential advantage for film dosimetry in radiotherapy, although transmission scanning mode is still recommended for dosimetry as it provides better uncertainty results. [ABSTRACT FROM AUTHOR]

Threshold-switching (TS) and selector performances of Si-As-Te thin films for crossbar resistive memory were studied. Composition of the film was the major factor determining the emergence of TS. On-state conduction was found to occur at localized regions. The change of threshold voltage and off-state current by varying composition was observed, which were explained by the change in the concentration of defects and generation efficiency of carriers. The serially connected TiO2 unipolar switching memory and Si-As-Te threshold switch showed the resistance switching of the memory layer with the leakage current lowered by ∼120 times at 0.5 V. [ABSTRACT FROM AUTHOR]

Silicon oxide thin film grown at low temperatures (<300-500 °C) is essential for a range of applications in semiconductor devices. In this study, silicon oxide films were deposited at a substrate temperature of ∼300 °C by an atomic layer deposition (ALD) process using Bis(ethyl-methyl-amino)silane (BEMAS). BEMAS precursors adsorbed on the growing surface reacted with ozone but not with H2O. This suggests that the Si-H bonds in the BEMAS precursors adsorbed on the surface are robust and could be cleaved only by ozone. The reaction using BEMAS and ozone exhibited ALD saturation behavior. The dielectric constant of the ALD-SiO2 was measured to be ∼9, which is 2.3 times higher than that (∼3.9) of normal amorphous SiO2. This was attributed to the existence of the ∼10% OH species in the film. [ABSTRACT FROM AUTHOR]

Tungsten (W) thin films were deposited using the modified chemical vapor deposition (CVD), the so-called pulsed CVD, and their properties were characterized as nucleation layers for the chemical vapor deposited W (CVD-W) technology of sub-50 nm memory devices. W growth per cycle was extremely linear with a higher growth rate of ∼0.58 nm/cycle as compared to that (∼0.28 nm/cycle) of the atomic layer deposition (ALD) process using the same chemistry. From the X-ray diffractometry, the pulsed CVD-W film was formed as an amorphous structure, which was the same as the atomic layer deposited W. This led to the formation of a low resistivity bulk CVD-W film deposited on it with the grain size of ∼180 nm at 200 nm thick film, and its resistivity was further decreased with the B2H6 post-treatment before the deposition of bulk CVD-W film (∼13 μΩ cm at a 50 nm thick film). However, we found that the adhesion performances of CVD-W growing on the B2H6-based pulsed CVD-W nucleation layer were significantly degraded as both the deposition temperature of the nucleation layer and the B2H6 post- treatment time increased. High resolution transmission electron microscopy and energy-dispersive spectroscopy analysis clearly demonstrated that a discontinuous boron layer was formed at the bulk CVD-W/nucleation layer interface, which was dominantly due to the B2H6 decomposition during the B2H6 post-treatment. We strongly suggest that a boron-containing discontinuous layer degrades the adhesion properties of CVD-W films growing on it. Considering the thermodynamics of the B2H6 decomposition, we can improve the adhesion properties by increasing the H2 flow rate at the post-treatment step. [ABSTRACT FROM AUTHOR]

Abstract: Two structures of low dielectric constant (low-k) SiOC films were elucidated in this work. Low-k thin film by remote plasma mode was mainly composed of inorganic Si–O–Si backbone bonds and some oxygen atoms are partially substituted by CH3, which lowers k value. The host matrix of low-k thin films deposited by direct plasma mode, however, was mainly composed of organic C–C bonds and “M” and “D” moieties of organosilicate building blocks, and thus the low dipole and ionic polarizabilities were the important factors on lowering k value. [Copyright &y& Elsevier]

Boron (B)-doped p + polycrystalline-silicongermanium (poly-Si 0.73 Ge 0.27 ) gate/AlN x / Al 2 O 3 /AlN x /n-Si metal-oxide-semiconductor (MOS) capacitors were fabricated in order to improve the blocking properties of B diffusion into the surface of an Al 2 O 3 film and the Si substrate by using in-situ atomic-layer-deposited (ALD) AlN x . The AlN x /Al 2 O 3 /AlN x stack film exhibited slightly better B diffusion-blocking properties as a result of the AlN x layers in the top and bottom interface layers of the Al 2 O 3 film. The B-doped poly-Si 0.73 Ge 0.27 gate/AlN x /Al 2 O 3 /AlN x /n-Si MOS capacitors had a lower current density of 3.8 × 10 -7 A/cm 2 at 1 V and a better reliability with an equivalent oxide thickness (Eot) of 2.45 nm due to the lower level of B penetration as a result of the AlN x and nitrogen incorporated interfacial silicon oxide (SiO x N y ) layers and the enhanced thermal stability. [ABSTRACT FROM AUTHOR]

Low-dielectric-constant (k) SiOC films were deposited on p-type (100) Si substrates by radio frequency (RF) PECVD with a bis-trimethylsilylmethane (BTMSM) precursor and oxygen gas. As more carbon was incorporated into the SiOC film, both the film density and refractive index decreased. This is because the decrease in film density on adding carbon in SiOC films resulted from termination of the Si&z.sbnd;O bonding network by replacing oxygen atoms with hydrocarbon groups. The bonding characteristics of low-k SiOC and SiOF films were investigated by Fourier-transform infrared (FTIR) spectroscopy. The Si&z.sbnd;O stretching vibration mode in SiOF films shifted to higher wavenumber with increasing fluorine incorporation, while that in SiOC films shifted to lower wavenumber as the carbon content increased. The origin of the low k of SiOC films was also investigated by determining the electronic, ionic and dipolar contributions. It was found that the low k of SiOC films mainly results from a reduction of the ionic contribution due to a decrease in Si&z.sbnd;O bonds in the films. Investigating the compatibility with integration processes showed that modification of the conventional process was required to improve the etch characteristics of the SiOC film. Post-deposition treatment of SiOC films in hydrogen plasma was effective. The results of this study show that SiOC film is very promising low-k material for interlayer dielectrics of multilevel interconnection. [Copyright &y& Elsevier]

We report the growth of high quality c-axis-oriented MgB2 thin films on Al2O3 substrates by using a pulsed laser deposition technique. The thin films show an onset transition temperature of 39.2 K with a sharp transition width of ∼0.15 K. X-ray diffraction patterns indicate a c-axis-oriented crystal structure perpendicular to the substrate surface. We observed high critical current densities (Jc) of ∼16 MA/cm2 at 15 K and under self-field, which is comparable to or exceeds those of cuprate high-temperature superconductors. The extrapolation Jc at 5 K was observed to be ∼40 MA/cm2, which is the highest record for MgB2 compounds. At a magnetic field of 5 T, the Jc of ∼0.1 MA/cm2 was detected at 15 K, suggesting that this compound is very promising candidate for the practical applications at high temperature with lower power consumption. As a possible explanation for the high current-carrying capability, the vortex-glass transition is considered. [Copyright &y& Elsevier]

We have analyzed about a hundred voltage-dependent differential resistance dV/dI(V) curves of metallic point contacts between c-axis-oriented MgB[sub 2] thin film and Ag, which exhibit clear Andreev reflection features connected with the superconducting gap. About one half of the curves show the presence of a second larger gap. The histogram of the double gap distribution reveals distinct maxima at 2.4 and 7 meV, while curves with single-gap features result in a more broad maximum at 3.5 meV. The double-gap distribution is in qualitative agreement with the distribution of gap values over the Fermi surface calculated by H.J. Choi etal. (cond-mat/0111183). The data unequivocally show the presence of two gaps: Δ[sub S] = 2.45±0.15 meV and Δ[sub L] = 7.0±0.45 meV in MgB[sub 2] with the gap ratio Δ[sub L]/Δ[sub S] = 2.85±0.15. Our observations further prove a widely discussed multigap scenario for MgB[sub 2], where two distinct gaps are seen in the clean limit, while a single averaged gap is present in the dirty one. © 2002 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

Thin films of polyimide (PI) were fabricated by a vapor deposition polymerization method (VDPM) and studied for their insulator characteristics in semiconductor devices. Polyamic acid (PAA) thin films fabricated by vapor deposition polymerization (VDP) from PMDA (pyromellitic dianhydride) and DDE (4,4′-diaminodiphenyl ether) were converted to PI thin films by thermal curing. The appropriate curing temperature was 300 °C. From TG-DTA (Thermo Gravimetry-Differential Thermal Analysis), the PI thin films can endure 230 °C for 20 000 h. They exhibited a relative permittivity of 3.9–3.5 and a dissipation loss factor of 0.008 at frequency of 10 kHz in the temperature range from 25 to 200 °C. The resistivity was approximately 3.2×1015 Ωcm and the dielectric breakdown strength was 4.61 MV/cm. [Copyright &y& Elsevier]

The authors measured magnetization hysteresis curves and used magneto-optical imaging to visualize the flux distributions in superconducting MgB2 films in order to study dendritic flux avalanches. The flux avalanches are found to disappear above some upper threshold field that is typically ∼1 kOe, but strongly depends on the film width. If the film is made wider, this threshold field first increases and then tends to saturate. This behavior is quantitatively explained using a thermomagnetic model for the dendritic avalanches and taking into account the field dependence of Jc. The results demonstrate that patterning superconducting films into narrow strips substantially increases the range of magnetic fields for which they can be used for applications. [ABSTRACT FROM AUTHOR]

• A newly synthesized water-soluble aromatic polyamide (WAPA) alignment layer. • Fabrication of liquid crystal (LC) cells with the WAPA films based on eco-friendly coating and low temperature annealing. • Measurements of voltage holding ratio, response time, and contrast ratio of the LC cells with the WAPA films. • Optical anisotropy effect of the WAPA alignment layer related with rubbing strength. A water-soluble aromatic polyamide (WAPA) thin film was formed by coating a newly synthesized poly(2,2′-disulfo-4,4′-benzidine isophthalamide) cesium salt (PDBI-Cs). Its electro-optical properties as an alignment layer in liquid crystal devices were analyzed. Twisted nematic-liquid crystal cells containing WAPA alignment layers annealed at a low temperature of 100 °C showed high voltage holding ratio values above 95 % at a frame rate of 60 Hz, a fast response time of 7.18 ms at ac operation of 1 kHz under LC-applied voltage of 5 V, and excellent contrast ratio of 3284 due to the high optical anisotropy effect of the WAPA surface. Thus, PDBI-Cs-based WAPA can be a promising candidate as a new eco-friendly low-temperature-processable alignment layer for flexible electro-optic devices. [ABSTRACT FROM AUTHOR]

We measured the superconducting critical current densities (J[sub c]) from the magnetization hysteresis (M–H) loop for Au-coated MgB[sub 2] thin films. The purpose of this experiment was to determine whether the vortex avalanche phenomenon which suppresses the J[sub c] for low temperature (T<15 K) and low field (H≤1000 Oe) could be cured by gold deposition. This avalanche, called flux noise, has been a headache in applications of MgB[sub 2] thin films. Fortunately, the flux noise in the M–H loop is suppressed with increasing Au-film thickness and finally disappears when the thickness of the gold becomes 2.55 μm. We found a way to remove one obstacle for applications of MgB[sub 2] thin films as an superconducting device. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Pb(Zr, Ti)O[sub 3] (PZT) thin films were deposited on Pt/Ti and Pt/IrO[sub 2] electrode stacks with various Pt thicknesses (30-200 nm) by a sol-gel process. The sputter-deposited Pt films showed a (111)-preferred texture irrespective of the thickness. However, a high-resolution x-ray diffraction study of the Pt films showed that the films were composed of three kinds of grains with slightly different lattice parameters. The grains with a bulk-like lattice parameter grew with increasing Pt thickness, which was accompanied with an improvement in the crystalline quality. Accordingly, the crystallization and ferroelectric behavior of the 100-nm-thick PZT films improved with increasing Pt film thickness. However, the PZT films on the Pt/IrO[sub 2] electrode showed a deteriorated ferroelectric performance due to the outward diffusion of the Ir (O) onto the Pt surface, which increases the depolarizing field and amount of charge injection by the formation of a conducting phase. [ABSTRACT FROM AUTHOR]

The electrical conduction behavior of sputter-grown (Ba, Sr)TiO[sub 3](BST) thin films having IrO[sub 2] electrodes were studied under the assumption of a fully accumulated film. In the film-thickness range studied (40-80 nm), the dielectric constants and their electric field dependencies were found to be independent of the film thickness. Contrary to similar BST films grown on Pt electrodes, the leakage current density decreased with increasing film thickness at a given field. The phenomena were explained from the electric-field depression effect inside the film due to the accumulated negative space charges in the films. The leakage current conductions were controlled by the Poole-Frenkel mechanism in the low field whereas it changed to thermionic field emission in the high-field region. The dielectric constant obtained from the Poole-Frenkel fitting was approximately 300, which was in a qualitative agreement with the value obtained from the low-frequency capacitance measurement. The calculated interfacial potential-barrier height at zero volt and effective mass of electrons were 1.03 eV and 0.06m[sub 0], respectively, from the thermionic field emission fittings. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

SrVO[sub 3] films were grown by laser molecular beam epitaxy on LaAlO[sub 3] substrates. For a 10-nm-thick film, its resistivity could be reduced by a factor of 4 by inserting a single La-O atomic layer on an oxygen-annealed LaAlO[sub 3] substrate. X-ray diffraction and x-ray photoelectron spectroscopy measurements revealed that oxygen defect concentrations could be varied significantly by controlling the substrate terminations, i.e., interface chemistry. It was suggested that the interface chemistry could influence formation of extended defects and result in changes in electrical properties. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A non-toxic and non-flammable organosilicon source having alternate Si–C bonding structure, bis-trimethylsilylmethane [C7H20Si2], was first used to deposit epitaxial β-SiC films at low growth temperature by chemical vapor deposition. Epitaxial β-SiC films were successfully grown on carburized Si(100) substrates at temperatures as low as 1100 °C, although the carburized buffer layer was a well-oriented, (100) polycrystalline film. Transmission electron microscopy analysis revealed that the films contain twins, stacking faults, and antiphase boundaries. Without the carburized buffer layer, highly (111) preferred oriented β-SiC films were grown by increasing the growth temperature. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We examined the electrical properties of low-temperature-processed top-gate In-Sn-Ga-O (ITGO) thin-film transistors (TFTs) by rf/dc -sputtering with different oxygen partial pressures (PO 2). As PO 2 changed from 0 to 50.0%, the ITGO TFT showed various electrical characteristics such as from conductor-like behavior to transfer curves with positive-shifted threshold voltages (V th). The TFT at PO 2 of 25.0% afforded the best performance, exhibiting field-effect mobility of 14.8 cm2V−1s−1, V th of 0.56 V, and subthreshold slope of 0.16 Vdec−1 with reasonable electrical stability for gate bias stress. From various analysis techniques, we found that the TFT characteristics and the electrical stability strongly depended on the metal-oxygen surface states of the ITGO films influenced by PO 2 during the sputtering process. • Electrical properties of In–Sn-Ga-O (ITGO) thin films with different annealing temperatures. • Fabrication of ITGO thin-film transistors (TFTs) by rf/dc -sputtering with different oxygen partial pressures (PO 2). • The changes of electrical characteristics of the ITGO TFTs with increasing PO 2 from 0 to 50.0%. • The TFT characteristics strongly depended on interface states of the ITGO films influenced by PO 2. [ABSTRACT FROM AUTHOR]

Abstract: The UV-O3 treatment effects on the structural properties of low-k films as a function of the treatment time were investigated in this study. The thickness of the samples proportionally decreased with the surface treatment time due to highly reactive ozone and the process gradually modified surface layer more SiO2-like. Excessive treatment of longer than 60 s adversely affected the low-k film, increasing the dielectric constant of underlying low-k film. After the UV-O3 treatment for the optimized treatment time of 60 s, the poor nucleation problem of Ru deposition was solved and fully-covered Ru film on low-k film was obtained. [Copyright &y& Elsevier]

We investigated the mixed-state magnetoresistance of high quality c-axis-oriented MgB2 thin films while varying the magnetic field and the current density. The temperature dependence of the magnetoresistance was well described by a vortex-glass theory for the low dissipative part of the resistivity and by a thermal fluctuation theory near the transition temperature. Interestingly, the observed thermally activated flux-flow region was very narrow or did not exist whereas, compared to conventional superconductors, the vortex-liquid phase was relatively broad in the H–T phase diagram. From the Werthamer–Helfand–Hohenberg theory, we obtained Hc2(0)=25.4 T, which was consistent with the value measured using a direct method. [Copyright &y& Elsevier]

We report the effect of annealing on the superconductivity of MgB2 thin films as a function of the postannealing temperature in the range from 700 to 950 °C and of the postannealing time in the range from 30 to 120 min. On annealing at 900 °C for 30 min, we obtained the best-quality MgB2 films with a transition temperature of 39 K and a critical current density of ∼107 A/cm2. Using scanning electron microscopy, we also investigated the film growth mechanism. The samples annealed at higher temperatures showed larger grain sizes, well-aligned crystal structures with preferential orientation along the c-axis, and smooth surface morphologies. However, a longer annealing time prevented the alignment of grains and reduced superconductivity, indicating a strong interfacial reaction between the substrate and the MgB2 film. [Copyright &y& Elsevier]

CuIn1−xGaxSe2 polycrystalline thin films were prepared by a two-step method. The metal precursors were deposited either sequentially or simultaneously using Cu–Ga (23 at%) alloy and In targets by DC magnetron sputtering. The Cu–In–Ga alloy precursor was deposited on glass or on Mo/glass substrates at either room temperature or 150°C. These metallic precursors were then selenized with Se pellets in a vacuum furnace. The CuIn1−xGaxSe2 films had a smooth surface morphology and a single chalcopyrite phase. [Copyright &y& Elsevier]

ZnO is of great interest for large-area optoelectronic devices, e.g., flat panel displays, light-emitting diodes, transparent semiconductors, and transparent conductive oxides (TCOs) etc., owing to its good optical properties. In the present study, quaternary ZnO thin films are deposited on a soda lime glass substrate using Mg and group III elements, such as Al, Ga, and In, to enhance the optical and electrical properties. The structural, optical, and electrical properties of quaternary ZnO TCO materials are investigated for improved thin film solar cell performance. All of the films show a uniform microstructure without any void and crack and have a transmittance over 75% in the visible region. They possess comparable band gap differences. Especially, as for the optical properties, a Mg and Ga co-doped ZnO, MgGaZnO (MGZO) thin film shows a high optical band gap of 3.87 eV with a transmittance of about 90% in the visible region. In addition, the MGZO thin film shows improved electrical properties with the lowest resistivity of 3.97 × 10−4 Ωcm, higher carrier concentration of 1.11 × 1021cm−3, high mobility of 14.07 cm2V−1s−1 and lower sheet resistance of 7.39Ω/sq. Moreover, a wide band gap of 3.87 eV is obtained for MGZO thin films, and the performance of a Cu 2 ZnSn(S, Se) 4 (CZTSSe) photovoltaic device fabricated with a MGZO TCO layer is improved owing to higher band gap and outstanding electronic properties. The improved short circuit current results in a device with a MGZO thin film with a power conversion efficiency of 8.79%. • Comparative study of quaternary transparent conducting oxide with Mg and different group III element (Al, Ga, In) was conducted. • Mg and group III elements co-doped ZnO were deposited on SLG by RF magnetron sputtering system. • The MGZO thin films showed resistivity of 3.97 × 10−4 Ωcm and optical band gap energy of 3.87 eV. • CZTSSe thin films solar cells with MGZO TCO layer showed higher efficiency of 8.79%. [ABSTRACT FROM AUTHOR]

We investigated the atomic configuration and the electronic structure of a BaBiO 3 (BBO) thin film and its (001) surface. It was theoretically predicted that two-dimensional electron gases would be formed when the film is BiO 2 -terminated. We deduced depth-profile information for a BBO thin film using angle-dependent X-ray photoemission spectroscopy. Analysis of the spectral weights of the Ba 3d and Bi 4 f core levels confirmed that the BBO film should have a BiO 2 -terminated topmost layer. We used in-situ angle-resolved photoemission spectroscopy to experimentally determine the electronic structure of a BBO thin film and found no metallic surface state. We distinguished surface states from bulk states by evaporating potassium atoms in-situ on the surface. A surface state near the bottom of the topmost bulk valence band, which was predicted by the DFT calculations, was identified. However, other surface states well separated from the bulk states were not observed. Our results provided evidence that descriptions of the BBO electronic structure require more detailed and elaborate approaches. [ABSTRACT FROM AUTHOR]

Abstract: Nitrided SiO2 has been thermally grown on n-type 4H silicon carbide substrate. The effects of post deposition annealing temperature (650 to 950 °C) in vacuum on physical properties of the oxides have been reported. Based on Fourier transform infra-red analysis, Si–O–Si bonding of the oxide has been weakened as the annealing temperature has been increased. The increment in annealing temperature has caused the increment in oxide thickness. Refractive index has been measured via Filmetric system and the index has been gradually reduced as a function of annealing temperature. This reduction trend is also being observed in the calculated values of film density and dielectric constant. In contrast, an increment trend has been recorded in film porosity as the annealing temperature increased. These observations may be attributed to the weakening of Si–O–Si bonding in the bulk oxide and roughening of the oxide surface, which has been demonstrated by atomic force microscopy. [Copyright &y& Elsevier]

Using a dielectric resonator technique the magnetic field penetration depth λ and the energy gap Δ of two MgB2 thin films were determined by measuring changes of resonance frequency with temperature. The exponential temperature dependence of λ is revealed at low temperatures (T, Tc is the critical temperature of the thin film). It indicates that a finite energy gap exists for thermal excitation of quasiparticles. From our measurements values of Δ/kTc=1.25 and λ0=290 nm for sample A and Δ/kTc=1.20 and λ0=160 nm for sample B give the best fit to the experimental results. The corresponding values for the energy gap Δ are 3.4 meV for sample A and 3.8 meV for sample B. In the high temperature region (T>Tc/2) the temperature dependence of λ can be well fitted by λ0/[1−(T/Tc)2]1/2. Our results strongly support the absence of nodes in the gap and a possible multigap scenario. [Copyright &y& Elsevier]

We report the measurement of magnetoresistance in a c-axis-oriented MgB2 thin film while varying the magnetic field and temperature. The scaling functions for the critical fluctuations were employed to analyze the excess conductance of these thin films. The fluctuating magnetoresistance, R(T,H), followed the 3D scaling suggested by Ullah and Dorsey. [Copyright &y& Elsevier]

The coherence peak is observed in the temperature dependence of the real part of the microwave conductivity (σ1) of c-axis oriented MgB2 thin film, which is extracted from microwave surface impedance (Zs) measurements using a sapphire resonator at 17.9 GHz. The peak appears at a temperature around 0.6 times the critical temperature (Tc), which is greatly shifted downwards in temperature compared with conventional superconductors for which the peak occurs around 0.9Tc. Calculations based on the two-band model suggest that this peak corresponds to the smaller of the two energy gaps. [Copyright &y& Elsevier]