Showing papers in "Semiconductor physics, quantum electronics and optoelectronics in 2003"
TL;DR: In this article, the formation of CaB4O7 compound is checked by X-ray diffraction study and the compound is found to have orthorhombic structure at room temperature.
Abstract: Abstract. Thermoluminescence of undoped and doped CaB4O7 with activators such as Cu and Mn has been investigated. The polycrystalline samples of undoped and doped CaB4O7 are prepared by melting method. The formation of CaB4O7 compound is checked by X-ray diffraction study and the compound is found to have orthorhombic structure at room temperature. The TSL studies of undoped CaB4O7 sample shows two glow peaks at 150°C and 265°C and one shoulder at around 190°C. The TSL studies of Cu doped CaB4O7 sample also shows two glow peaks at 160°C and 270°C and a shoulder at around 230°C whereas the TSL glow curves of Mn doped CaB4O7 has only one single strong glow peak at 135°C. A comparative TSL studies of these compounds shows that CaB4O7 compound doped with Mn is the most sensitive and the TSL intensity is enhanced by about 40 times when compared with the TSL intensity of undoped CaB4O7 compound. The trap parameters namely order of kinetics (b), activation energy (E) and frequency factor (s) associated with the 135°C glow peak of CaB4O7: Mn phosphor are determined using isothermal decay and glow curve shape (Chens) methods.
27 citations
24 citations
TL;DR: In this article, multilayer antireflection coatings have been modeled in visible and IR (3n5μm) bands to reduce reflectance from glass, germanium (Ge), silicon (Si), and zinc selenide (ZnSe) substrates.
Abstract: Multilayer antireflection coatings have been modeled in visible and IR (3n5μm) bands to reduce reflectance from glass, germanium (Ge), silicon (Si) and zinc selenide (ZnSe) substrates. The transmittance of bare glass substrate is around 95% whereas for Ge 64%, Si 70%, ZnSe 84%. Theses values are enhanced reasonably by the application of multilayers films. Starting from a single layer, the layers have been added systematically forming multilayer structures to reduce reflectance considerably with each increasing layer. The designed layers are optimized for their performance by varying their thickness and refractive indices. The analysis of these modals has shown that the proposed multilayer structures are very effective in reducing the reflectance for all the substrates in two spectra.
19 citations
12 citations
12 citations
Abstract: A mechanism for creation of microrelief surface anisotropy of amorphous films oxides materials which are obtained by oblique reactive cathode sputtering method is described. The influence of technological parameters of sputtering on the LC orienting parameters is investigated. The dependencies of the target material, angle of material emission and reemission processes under the substrate negative ion treatment is shown. The application of oblique reactive cathode sputtering method for creation of LCD with differ-ent size is demonstrated.
7 citations
6 citations
TL;DR: In this paper, the Tikhonov regularization method was used to solve the Fredholm 1st rank equation to determine the localized state energy distribution function for semiconducting solid materials based on space-charge-limited currentvoltage characteristics.
Abstract: The paper provides the direct experimental method to determine the localized state energy distribution function for semiconducting solid materials based on space-charge-limited current-voltage characteristics. The current-voltage characteristics would be obtained under the random temperatures. The Tikhonov regularization method was used to solve the Fredholm 1st rank equation. The method developed in this research was used for the study of deep traps in CdTe polycrystalline films obtained in quasi-closed-tube on the conducting substrate. In the bend gap of the material, some traps were traced, which can be described by the close to Gaussian distribution parameters as well as by the parameter of energy disorder = 0.0150.04 åV. The research shows that the trap concentration and depend on the physical and technological conditions of the obtained films, while the energy of the traps depends on the impurity-defective material structure.
6 citations
TL;DR: In this paper, a technique of formation of homogeneous nanoporous silicon layers with high internal surface on solar cell substrates by stain etching is developed, and the emission and structure properties of such layers were studied by photoluminescence (PL), photolUMinescence excitation, Auger electronic spectroscopy, atomic force microscopy and scanning tunnel microscopy methods.
Abstract: In this work, the technique of formation of homogeneous nanoporous silicon layers with high internal surface on solar cell substrates by stain etching is developed. Emission and structure properties of such layers were studied by photoluminescence (PL), photoluminescence excitation, Auger electronic spectroscopy, atomic force microscopy and scanning tunnel microscopy methods. It was observed that nanoporous layers are of high homogeneity and their thickness is ~2025 nm. It was shown that the higher PL intensity of such layers in comparison with PL intensity of the layers prepared on standard substrates in the same regimes is connected with the higher internal surface. The increase of PL intensity during prolonged aging in air at the room temperature was observed.
Abstract: Voltage-current characteristics forwardly biased heterojunctions p-GaSe-n-InSe made by the method of optical contact are analyzed. Asit was ascertained, the forward current is determined by tunnel-recombination processes at low voltages and overbarrier emission. The experimental characteristics are defined by the known theoretical expressions for anisotipical heterojunctions with the energy diagram by Andersen.