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Characterization of CuInSTe/CdS Heterojunctions
摘要： In this work, the role of substrate temperature in the range (293-423)K on the structure and microstructure of CuInSTe thin films was investigated. The results showed that the structure was amorphous for films prepared at ambient temperature Ts=293Kwhile it was polycrystalline for films prepared at high temperature. The grain size and roughness increased with increasing substrate temperature. The frequency and temperature dependencies upon AC conductivity were investigated in the frequency range 100Hz-10MHz and temperature of heat treatment in the range of 303-453K. The AC activation energy was found to increase from 0.1132 to 0.1258 eV with increasing substrate temperature from 293 to 423K and decrease to 0.0962 eV with increasing frequency from 100 to 107 Hz. The exponents show a nonsystematic sequence with the increment of substrate temperature. The obtained results gave indication t hat there is a relation between the structure and preparation temperature as well as heat treatment. According to the current-voltage characteristic, the CuInSTe/CdS heterojunction prepared at substrate temperature of 423K showed the best electrical characteristics under illumination conditions.
关键词： Activation energy,Heterojunction,quaternary alloy CuInSTe,dielectric properties,Thin films
更新于2025-09-10 09:29:36
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Thermal annealing induced evolution of AgIn5Se8 phase from Ag/In2Se3 bilayer thin film
摘要： In the present report, we have investigated the AgIn5Se8 phase formation upon annealing the Ag/In2Se3 bilayer film prepared by the thermal evaporation technique. The optical, morphology as well as structural parameters was tuned with different annealing temperature. The prominent crystalline phase developed at 2500C annealing where as there is no signal of this phase in the as-prepared film (amorphous). The analysis using XRD study showed the amorphous to crystalline phase transformation with annealing. The indirect as well as the direct band gap is found to be increased with annealing (up to 1500C) and then decreased due to the growing up new phase as explained by phase transformation and decrease in density of localized states. The formation of dangling bonds at the surface near the crystallite sites during crystallization process reduces the band gap. The Tauc parameter change shows the degree of chemical disorderness in the films. The transmitivity, absorption coefficient, oscillator energy, refractive index, dispersion energy and extinction coefficient are found to be changed accordingly with annealing condition.The micro structural study done by Scanning Electron Microscopyshows the formation of crystallites upon annealing. The Raman study of these films supports the formation of new phase.
关键词： bandgap,Thin films,annealing,optical properties,chalcopyrite,structural properties
更新于2025-09-10 09:29:36
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Evolutions on surface chemistry, microstructure, morphology and electrical characteristics of SnO2/p-Si heterojuction under various annealing parameters
摘要： The influences of annealing temperature and ambient on surface chemistry, microstructure, morphology and electrical characteristics of Tin Oxide (SnO2)/Si heterojuctions are systematically identified. Metallic and oxygen deficient SnO2-x bonds have been consistently treated to stoichiometric SnO2 with annealing temperatures up to 600 0C in nitrogen environment. It has been observed that further increase in the annealing temperature causes the formation of the silicate layer. Presence of hydrogen in forming gas environment causes formation of the oxygen deficient SnO2-x, while the presence of the oxygen contributes to the formation of the stoichiometric SnO2 layer in oxygen annealing ambient. Parasitic phases significantly affect the crystalline structure of the films. Surface roughness of the samples decreases up to 1.02 nm which is strongly correlated with stress and strain on the film. On the other hand, oxidations of the dangling bonds and/or hydrogen diffusion cause variations in the total dipole moments which significantly change the capacitance. Depending on the annealing parameters, effective charge densities and interface trap densities decrease to 1011 cm-2, while the ideality factor and barrier potential are improved to 1.43 and 0.59 eV, respectively. Owing to the crystallization of the SnO2 layer, leakage current increase at low temperature annealing. However, passivation of the dangling bonds becomes more effective than phase crystallization at higher temperatures on the leakage characteristics. The current study shows that any changes in the surface chemistry directly affect the device performance.
关键词： Tin Oxide,XPS,Oxide Films.,Heterojuction,Surface Chemistry,Annealing
更新于2025-09-10 09:29:36
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Atomic-layer-deposited (ALD) Al2O3 passivation dependent interface chemistry, band alignment and electrical properties of HfYO/Si gate stacks
摘要： In this work, the effects of atomic-layer-deposited (ALD) Al2O3 passivation layers with different thicknesses on the interface chemistry and electrical properties of sputtering-derived HfYO gate dielectrics on Si substrates have been investigated. The results of electrical measurements and X-ray photoelectron sepectroscopy (XPS) showed that 1-nm-thick Al2O3 passivation layer is optimized to obtain excellent interfacial properties for HfYO/Si gate stack. Then, the metal-oxide-semiconductor capacitors with HfYO/1-nm Al2O3/Si/Al gate stack were fabricated and annealed at different temperatures in forming gas (95% N2+5% H2). Capacitance-voltage (C-V) and current density-voltage (J-V) characteristics showed that the 250oC-annealed HYO high-k gate dielectric thin film demonstrated the lowest border trapped oxide charge density (-3.3 × 1010 cm-2), smallest gate-leakage current (2.45 × 10-6 A/cm2 at 2 V) compared with other samples. Moreover, the annealing temperature dependent leakage current conduction mechanism for Al/HfYO/Al2O3/Si/Al MOS capacitor has been investigated systematically. Detailed electrical measurements reveal that Poole-Frenkle emission is the main dominant emission in the region of low and medium electric fields while direct tunneling is dominant conduction mechanism at high electric fields.
关键词： Al2O3 passivation layer,Electrical properties,Annealing,Co-sputtering HYO films,Conduction mechanism
更新于2025-09-10 09:29:36
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Heat-Treatment Induced Magnetic Anisotropy of GaMnSb Films
摘要： Conditions and mechanisms of controlled variation of the magnetic anisotropy of GaMnSb films containing magnetic MnSb nanoinclusions by means of heat treatment have been determined. For this purpose, the temperature and magnetic-field dependences of the magnetic moments of samples before and after thermal annealing were measured using a SQUID magnetometer. It is established that the heat treatment of GaMnSb films leads to a significant increase in the values of characteristics determined by the magnetic anisotropy, including the growth of blocking temperature (from 95 to 390 K) and the magnetic anisotropy field (from 330 to 630 Oe). Results of transmission electron microscopy investigation indicate that a change in the magnetic anisotropy of GaMnSb films as a result of their thermal annealing can be related to a transition of the crystalline structure of magnetic MnSb nanoinclusions from hexagonal (space group P62/mmc) to cubic (space group F-43m).
关键词： magnetic anisotropy,GaMnSb films,SQUID magnetometer,transmission electron microscopy,MnSb nanoinclusions,heat treatment
更新于2025-09-10 09:29:36
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Low-Temperature CVD Graphene Nanostructures on Cu and Their Corrosion Properties
摘要： Chemical vapor deposition (CVD) graphene is reported to effectively prevent the penetration of outer factors and insulate the underneath metals, hence achieving an anticorrosion purpose. However, there is little knowledge about their characteristics and corresponding corrosion properties, especially for those prepared under different parameters at low temperatures. Using electron cyclotron resonance chemical vapor deposition (ECR-CVD), we can successfully prepare graphene nanostructures on copper (Cu) at temperatures lower than 600 ?C. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and potentiodynamic polarization measurements were used to characterize these samples. In simulated seawater, i.e., 3.5 wt.% sodium chloride (NaCl) solution, the corrosion current density of one graphene-coated Cu fabricated at 400 ?C can be 1.16 × 10?5 A/cm2, which is one order of magnitude lower than that of pure Cu. Moreover, the existence of tall graphene nanowalls was found not to be beneficial to the protection as a consequence of their layered orientation. These correlations among the morphology, structure, and corrosion properties of graphene nanostructures were investigated in this study. Therefore, the enhanced corrosion resistance in selected cases suggests that the low-temperature CVD graphene under appropriate conditions would be able to protect metal substrates against corrosion.
关键词： graphene films,corrosion,copper,low temperature,chemical vapor deposition
更新于2025-09-10 09:29:36
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Aggregation States of Organic Dye Molecules in Organic – Inorganic Hybrid Films Studied by Near-Field and Far-Field Fluorescence Spectroscopy
摘要： Near-field fluorescence spectroscopy in conjunction with far-field fluorescence and Raman spectroscopy has been applied to investigate the aggregation states of cyanine dye of 2-[5-(1,3-Dihydro-3,3-dimethyl-1-octadecyl-2H-indol-2-ylidene)-1,3-pentadienyl]-3,3-dimethyl-1-octadecyl-3H-indolium perchlorate (NK3175) molecules in the depth direction, from the nanometer-scale top surface to the bulk, in the hybrid films consisted of NK3175 and a clay compound (SWN). The far-field Raman spectra reveal that these hybrid films contained both NK3175 molecules which did not take part in the adsorption and those adsorbed on SWN. The near-field photoluminescence (PL) spectra in the outermost surface within ca. 30 nm exhibit a significant blue shift for the hybrid films as compared to their respective PL spectra in the bulk, implying that the top surface of these hybrid films becomes more polar and/or rigid in terms of the microenvironment around NK3175 molecules compared to the bulk of them, in contrast to the case for the other hybrid film which was prepared by the alternative method. These results provide new information on the aggregation states of organic dye molecules not only in the bulk but in the nanometer-scale top surface of organic-inorganic hybrid systems.
关键词： far-field fluorescence,Raman spectroscopy,organic-inorganic hybrid films,aggregation states,Near-field fluorescence spectroscopy,cyanine dye
更新于2025-09-10 09:29:36
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Optical Properties of Fe <sub/>3</sub> O <sub/>4</sub> Thin Films Prepared from the Iron Sand by Spin Coating Method
摘要： Research on magnetic oxide is growing very rapidly. This magnetic oxide can be found in nature that is in iron sand. One of the beaches in Sumatera Barat containing iron sand is Tiram Beach, Padang Pariaman District, Sumatera Barat. The content of iron sand is generally in the form of magnetic minerals such as magnetite, hematite, and maghemit. Magnetite has superior properties that can be developed into thin films. The purpose of this research is to investigate the optical properties of transmittance, absorbance, reflectance and energy gap from Fe3O4 thin films. This type of research is an experimental research. The iron sand obtained from nature is first purified using a permanent magnet, then made in nanoparticle size using HEM-E3D with milling time for 30 hours. After that, the process of making thin film with sol-gel spin coating method. In this research, variation of rotation speed from spin coating is 1000 rpm, 2000 rpm and 3000 rpm. Based on XRD results indicated that the iron sand of Tiram beach contains magnetite minerals and the SEM results show that the thickness of the thin films formed is 25μm, 24μm and 11μm. The characterization tool used for characterizing optical properties is the UV-VIS Spectrophotometer. So it can be concluded that the greater the speed of rotation the thickness of the thin layer will be smaller, resulting in the transmittance and reflectance will be greater, while the absorbance will be smaller. Energy gap obtained from this research is 3,75eV, 3,75eV and 3,74eV. So the average energy gap obtained is 3,75eV.
关键词： Fe3O4,energy gap,optical properties,thin films,spin coating
更新于2025-09-10 09:29:36
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Effect of Cadmium Dopant on Structure and Optical Properties of ZnO Thin Films Prepared by Spray Pyrolysis Technique
摘要： Effect of Cadmium Dopant on Structure and Optical Properties of ZnO Thin Films Prepared by Spray Pyrolysis Technique
关键词： Spray Pyrolysis Technique,Optical Properties,ZnO Thin Films,Cadmium Dopant
更新于2025-09-10 09:29:36
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Anomalous Hall-like transverse magnetoresistance in Au thin films on Y <sub/>3</sub> Fe <sub/>5</sub> O <sub/>12</sub>
摘要： Anomalous Hall-like signals in platinum in contact with magnetic insulators are common observations that could be explained by either proximity magnetization or spin Hall magnetoresistance (SMR). In this work, longitudinal and transverse magnetoresistances are measured in a pure gold thin film on the ferrimagnetic insulator Y3Fe5O12 (Yttrium Iron Garnet, YIG). We show that both the longitudinal and transverse magnetoresistances have quantitatively consistent scaling in YIG/Au and in a YIG/Pt reference system when applying the SMR framework. No contribution of an anomalous Hall effect due to the magnetic proximity effect is evident.
关键词： gold thin films,Anomalous Hall effect,Y3Fe5O12,proximity magnetization,spin Hall magnetoresistance
更新于2025-09-09 09:28:46