نتایج جستجو برای: band gap
تعداد نتایج: 261994 فیلتر نتایج به سال:
In this research, zinc oxide thin films with gallium impurity have been deposited using the spray pyrolysis technique. The structural and optical properties of these films are investigated as a function of gallium doping concentrations. The ZnO and ZnO:Ga films grown at a substrate temperature of 350 ºC with gallium doping concentrations from 1.0 to 5.0.%. The XRD analysis indicated that ZnO f...
In this paper, undoped TiO2 and Ag-Nd-codoped TiO2 nanocomposites with different molar ratios of dopants were synthesized by the sol-gel method using starch as a natural additive. Structures were investigated by FT-IR and UV–Vis spectroscopy, SEM, and XRD methods. Moreover, the direct band gap was calculated by Tauc's approach. Furthermore, photocatalytic activity of all s...
In this article, we considered the field analysis in photonic crystal Bragg fibers. We apply the method of transmission matrix to calculater the dispersion curves, the longitudinal wave number over wave number versus incident wavelength, and the field distributions of TE and TM modes in the Bragg fiber. Our analysis shows that the field of guided modes is confined in the core and can exist onl...
The electronic and structural properties of CaS are calculated using full potential linearized augmented plane wave (FP-LAPW) method within the local density approximation (LDA) and generalized gradient approximation (GGA) for the exchange-correlation energy. For both structures, NaCl structure (B1) and CsCl structure (B2), the obtained values for lattice parameters, Bulk modulus and its pres...
Optical absorption edge measurements are performed on I doped PbTe using diffuse reflectance infrared Fourier transform spectroscopy. The Burstein–Moss shift, an increase in the absorption edge (optical band gap) with increasing doping level, is explored. The optical gap increases on the order of 0.1 eV for doping levels ranging from 3× 1018 to 2× 1020 cm−3, relevant doping levels for good ther...
The promising photovoltaic activity of pyrite (FeS2) is attributed to its excellent optical absorptivity and earth abundance, but its band gap, 0.95 eV, is slightly lower than the optimum value of 1.3 eV. Here we report the first investigation of strained FeS2, whose band gap can be increased by ∼0.3 eV. The influence of uniaxial and biaxial strains on the atomic structure as well as the electr...
Abstract: Different thickness of Cu2S thin films were prepared by vacuum evaporation under a pressure of 10-6 torr at an evaporation rate of 3Å /sec. Cu2S has direct band gap energy and indirect band gap energy at 1.2eV and 1.8 eV respectively. This paper presents the analysis of structural and optical properties of the Cu2S thin film by X-ray diffractometer (XRD) and UV-Vis-NIR Spectrophotomet...
In this paper size effects, growth orientation and also doping by Ammonia molecule (NH3) on the carbon nanowire properties with saturated diamond structure by (DNw:H) have been investigated. This study was carried out using DFT theory and Kohn-Sham equation by self-consistent field (SCF) that performed by local density approximation (LDA). The nanowires morphology is cylindrical with [111] grow...
In this paper size effects, growth orientation and also doping by Ammonia molecule (NH3) on the carbon nanowire properties with saturated diamond structure by (DNw:H) have been investigated. This study was carried out using DFT theory and Kohn-Sham equation by self-consistent field (SCF) that performed by local density approximation (LDA). The nanowires morphology is cylindrical with [111] grow...
In the present study, ZnO nanostructure has been synthesized by different methods, namely coprecipitation, hydrothermal and sonochemical methods. After comparison of the morphology and photocatalytic activity of ZnO samples prepared via different methods, the best method (sonochemical method) was used for synthesis of Ni-ZnO nanoparticles with different concentrations of nickel. Furthermore, st...
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