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Field Effect in PbSnTe:In Films with Low Conductivity in the Mode of Injection from Contacts and Space-Charge Limitation of the Current
摘要： At T = 4.2 K, a strong change (up to 4 times) in the space-charge-limited current (SCLC) is observed for the first time at samples based on semi-insulating PbSnTe:In films grown by molecular-beam epitaxy on BaF2(111) substrates. The obtained results agree with experiments on the effect of treatment of the surface of PbSnTe:In films on the space-charge-limited current with a variation in the current to 103 times or more. At a qualitative level, the model is considered which assumes the substantial contribution of localized surface states to space charge formed in the mode of space-charge-limited current due to the injection of charge carriers from contacts.
关键词： field effect,surface states,molecular-beam epitaxy,space-charge-limited current,PbSnTe:In films
更新于2025-09-10 09:29:36
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Polycrystalline diamond films with tailored micro/nanostructure/doping for new large area film-based diamond electronics
摘要： This paper describes processes developed to change two key electrical properties (electrical resistivity and carrier type) of ultrananocrystalline diamond (UNCD) to microcrystalline diamond (MCD) films. The results show that the electrical properties of the investigated polycrystalline diamond films depend on the grain size and plasma treated grain boundary networks interfaces and external films’ surfaces, in which hydrogen, fluorine or nitrogen can be incorporated to tailor electrical carriers-type to tune the electrical properties. Exploring the feasibility of modulating the resistivity of polycrystalline diamond films via tailoring of grain size, surface chemistry and nitrogen or fluorine incorporation into films’ grain boundaries and external surfaces may enable applications of these diamond films as active or heat dissipation layers on micro/nano-electronic devices. This work can open the pathway to enabling an industrial process for new diamond-based electronics, since polycrystalline diamond films can be grown with extreme uniformity on 300 mm diameter Si wafers, used in manufacturing of current Si-based micro/nano-electronic devices.
关键词： Nitrogen incorporation,Diamond-based electronics,Electrical properties,Plasma treatment,Fluorine incorporation,Grain size,Polycrystalline diamond films
更新于2025-09-10 09:29:36
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Optical and mechanical properties of Sol-gel prepared Titania (TiO <sub/>2</sub> ) –Silica (SiO <sub/>2</sub> ) mixed thin films ‘as prepared at 300 K’ without any post heat treatment
摘要： The mixed metal oxide (MMO) thin films like titania-silica (TiO2–SiO2) prepared by sol-gel technology have shown a variety of interesting optical, mechanical and thermo-mechanical properties; these thin films are being used in a variety of applications. In the present investigation, the TiO2–SiO2 (TS) thin films (on glass substrates) are prepared at 300 K from non-aqueous individual sols of TiO2 and SiO2 of 0.1 molar (TS-1) and 0.3 molar (TS-3) concentrations; no post heat treatment has been conducted on these films. The thicknesses of the two layer (2 l) and four layer (4 L) thin films prepared by dip coating are in the range 27 nm to 170 nm. The optical and mechanical properties of these ‘as-deposited’ thin films have been evaluated. The ‘as-deposited’ TS thin films show an optical transparency (in the visible region) of ～90% and optical band gaps are in the range 4.44 eV to 4.50 eV. The optical density has been calculated from the refractive index measurements. The refractive index of TS-1 thin films of thickness 27 nm is practically constant at 1.61 over the wavelength range 400–750 nm. Micro-cracks have been observed (Scanning electron micrographs) in TS-1-4L and TS-3-4L thin films. These micro cracks are more significant in TS-3-4L samples than those of TS-1-4L samples. These cracks are not seen in all other samples (TS-1-2L and TS-3-2L). These mixed titania-silica thin films show higher adherence and higher hardness compared to those of TiO2 thin films. The Raman spectroscopy measurements show the existence of multiple phases of Ti–O–Si. It is known that in the multi-phase structures, the phase boundaries hinder crack propagation and enhances the resistance to plastic deformation enhancing the mechanical hardness of these TS thin films.
关键词： Sol-gel,mechanical properties,optical properties,titania-silica thin films
更新于2025-09-10 09:29:36
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Ligand Shell Engineering to Achieve Optimal Photoalignment of Semiconductor Quantum Rods for Liquid Crystal Displays
摘要： The photoalignment process to align semiconductor quantum rods (QRs) in the liquid crystal monomer (LCM) matrix is a flexible technology; however, the optical quality of the resulting enhancement films drops at high concentrations of the QRs. The compatibility between the ligand shell on the QRs and the LCM plays an important role in avoiding this issue. Herein, several kinds of ligand shells on the rod-in-rod CdSe/CdS QRs are designed, without affecting the optical properties of QRs, and their compatibility with LCM molecules is studied. Promesogenic dendritic ligands in combination with relatively short alkylphosphonic acids are found to provide the highest optical quality, without QR aggregation, and so the high brightness of the resulting enhancement films, even at higher concentrations of QRs in LCM, which is perfectly suitable for the application in liquid crystal displays.
关键词： photoalignment,enhancement films,ligand design,quantum rods,liquid crystal displays
更新于2025-09-10 09:29:36
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Optical and Magneto-Optical Properties of Multilayer Nanosized [Co/TiO2]n Films
摘要： The optical and magneto-optical properties of the metal–dielectric multilayer [Co/TiO2]n structures with 2–4-nm-thick layers prepared on a silicon substrate Si(001) by ion-beam deposition have been studied. The complex permittivity of multilayer [Co/TiO2]n structures has been measured by the optical ellipsometry technique in the spectral range of 0.6–5.6 eV and analyzed using the optical reflection matrices for isotropic multilayer dielectric structures taking into account the optical losses and also using the method of anisotropic effective medium. The magneto-optical Kerr effect has been measured by the polarimetric technique in the spectral range of 1.2–4.5 eV in the polar and longitudinal geometries. The magnetic anisotropy type is determined on the base of the field dependences of the magneto-optical Kerr effect. It is found that the nanosized [Co/TiO2]n structures can be considered as artificial optically uniaxial media with a strong magnetic and optical anisotropy at room temperature.
关键词： silicon substrate,Co/TiO2,magneto-optical properties,multilayer nanosized films,optical properties,complex permittivity,magneto-optical Kerr effect,magnetic anisotropy,optical ellipsometry,ion-beam deposition
更新于2025-09-10 09:29:36
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Structure and properties of Mn3O4 thin films grown on single crystal substrates by chemical vapor deposition
摘要： Mn3O4 thin films were fabricated on SrTiO3(111) and Y3Al5O12(100) substrates by chemical vapor deposition (CVD) under O2 atmospheres, starting from a fluorinated Mn(II) diketonate-diamine adduct. The obtained systems were investigated by a multi-technique characterization in order to elucidate the interplay between preparation conditions and their chemico-physical properties. The results highlighted the formation of phase-pure and homogeneous a -Mn3O4 (haussmannite) films, characterized by a smooth morphology, an appreciable Vis light absorption and structural features directly dependent on the used substrate. The target systems were uniformly doped with fluorine, due to the used Mn compound acting as a single-source precursor for both Mn and F. In addition, magnetic force microscopy measurements revealed the formation of spin domains and long-range magnetic order in the target materials, paving the way to their future implementation as magnetic media toward device integration for data storage.
关键词： Y3Al5O12(100),SrTiO3(111),Mn3O4 thin films,chemical vapor deposition,magnetic materials
更新于2025-09-10 09:29:36
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Effect of gamma irradiation dose on the structure and pH sensitivity of ITO thin films in extended gate field effect transistor
摘要： Even though several studies have demonstrated the use of Indium Tin Oxides (ITO) as an extended gate field effect transistor (EGFET), the effect of different doses of gamma radiation on the intrinsic properties of the ITO films has not been considered. This study investigates the effect of gamma irradiation on the structural, optical, morphological and electrical properties as well as pH sensitivity (as an extended gate field effect transistor) of ITO thin films. ITO thin films with thickness of 400 nm were prepared using a radio frequency sputtering technique. The samples were then subjected to various doses of gamma radiation from a Co-60 radio-isotope (0.5 kGy, 1 kGy, 1.5 kGy, and 2 kGy). The structural and morphological changes as well as transmission and absorption of the thin films were analyzed using X-ray diffraction (XRD), Atomic Force Microscopy (AFM), Field-Emission Scanning Electron Microscope (FESEM) and UV-Vis spectrophotometry, before and after irradiation. The irradiated ITO thin films were then used as an extended gate field effect transistor to determine its ability to improve sensitivity as pH sensors. The grain size and transmittance in the range 300-900 nm of the ITO films were found to decrease with increasing gamma irradiation dose. In contrast, the uniformity and surface roughness of ITO thin films increased with increasing gamma radiation dose due to the formation of lattice defects. Moreover, the electrical resistance of the thin films increased with increasing dose because of the low current density and high number of surface defects associated with irradiation. The pH sensitivity of the ITO thin films improved after irradiation, possibly due to the concomitant increase in surface roughness with increasing radiation dose. The improvements in the pH sensitivity of ITO thin films after irradiation justify their potential use as pH sensors.
关键词： EGFET,pH sensor,Optical band gap,Gamma irradiation,X-ray diffraction,Indium Tin Oxide,Thin films
更新于2025-09-10 09:29:36
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Growth and properties of CdZnTe films on different substrates
摘要： High quality CdZnTe films were deposited on polished CdZnTe film, Si wafer and fluorine doped tin oxide (FTO) glass by close spaced sublimation (CSS) method. The influences of different substrates on the growth rate, composition, structural and electrical properties of CdZnTe films were investigated. The results showed that the CdZnTe film prepared on the polished CdZnTe film substrate had a higher growth rate and a better crystalline quality. The film prepared on the polished CdZnTe film substrate also exhibited lower leakage current, which is promising for high energy particle detection.
关键词： Close spaced sublimation method,Substrates,CdZnTe films
更新于2025-09-10 09:29:36
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(TiO <sub/>2</sub> ) <sub/>1?x</sub> (TaON) <sub/>x</sub> Solid Solution for Band Engineering of Anatase TiO <sub/>2</sub>
摘要： Band engineering of anatase TiO2 was achieved by means of an anatase (TiO2)1?x(TaON)x (TTON) solid solution. Epitaxial thin films of TTON (0.1 ≤ x ≤ 0.9) were synthesized by nitrogen plasma-assisted pulsed laser deposition on (LaAlO3)0.3(SrAl0.5Ta0.5O3)0.7 substrates. Epitaxial growth of anatase TTON was confirmed by X-ray diffraction. The lattice constants of the TTON thin films increased with TaON content in accordance with Vegard’s law, indicating formation of a complete solid solution. The bandgaps, band alignment, and refractive indices of the TTON thin films were investigated by combination of spectroscopic ellipsometry and X-ray photoelectron spectroscopy. The bandgap of the anatase TTON systematically decreased with increasing x, mainly because of an upward shift in the valence band maximum caused by broadening of the valence band as a result of hybridization of the shallow N 2p orbital. The position of the conduction band minimum was rather insensitive to chemical composition, which makes the band alignment of anatase TTON suitable for photocatalytic water splitting with visible light. The refractive index of anatase TTON monotonically increased with an increase in x.
关键词： Epitaxial thin films,Vegard’s law,X-ray photoelectron spectroscopy,TTON solid solution,Band engineering,Photocatalytic water splitting,Spectroscopic ellipsometry,Nitrogen plasma-assisted pulsed laser deposition,Anatase TiO2
更新于2025-09-10 09:29:36
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High-speed Fizeau interferometry for film topography measurement during spray film interaction
摘要： This work presents a novel high-speed interferometric thickness measurement system for thin films (1 μm-23 μm). The system is based on a Fizeau-interferometer and combines a high-speed camera for 2-D topographic fringe images with a spectrally resolved white light interferometer. The aim of this combination is to overcome the ambiguities of the phase demodulation process during fringe pattern analysis. The system is able to measure spatially and temporally resolved film thickness distributions during fast processes. The measurement error of the system is around 5% compared to a commercial 0-D interferometer. First, the results during a diesel spray impingement onto a predefined diesel film are shown, and at the impingement point, an increase in a fluid volume of 24.3% can be seen.
关键词： interferometric thickness measurement,High-speed Fizeau interferometry,thin films,spray film interaction,film topography measurement
更新于2025-09-10 09:29:36