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Band Gap Energy (band + gap_energy)

Distribution by Scientific Domains

Physics and Astronomy	100%

Selected Abstracts

Temperature-tuned band gap energy and oscillator parameters of Tl2InGaSe4 semiconducting layered single crystals

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2009
N. M. Gasanly
Abstract The optical properties of Tl2InGaSe4 layered single crystals have been studied through the transmission and reflection measurements in the wavelength range of 500-1100 nm. The analysis of room temperature absorption data revealed the presence of both optical indirect and direct transitions with band gap energies of 1.86 and 2.05 eV, respectively. Transmission measurements carried out in the temperature range of 10-300 K revealed that the rate of change of the indirect band gap with temperature is , = , 4.4 × 10 -4 eV/K. The absolute zero value of the band gap energy was obtained as Egi(0) = 1.95 eV. The dispersion of the refractive index is discussed in terms of the single oscillator model. The refractive index dispersion parameters: oscillator wavelength and strength were found to be 2.53 × 10,7 m and 9.64 × 1013 m,2, respectively. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Studies on structural and optical properties of Cu-Sb-O thin films

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2010
Nadia Chaglabou
Abstract We report in this paper the structural and optical properties of Cu-Sb-O thin films systems. Samples were prepared via sequential thermal vacuum deposition of Cu and Sb or Sb and Cu (10 -5 Torr) on glass substrates after what they were heated in vacuum at 200 °C for 1 hour. So, the obtained intermetallic multilayer systems (Cu/Sb)j=1,2,3 and (Sb/Cu)j=1,2,3 were annealed in air atmosphere between 30°C and 400 °C for 3 h for j=1; for 6 h for j=2 and for 9 h for j=3. These films were characterized for their structural, surface morphological, compositional, and optical properties by using X-ray diffraction (XRD) and optical (transmittance and reflectance) measurement techniques. The X-ray diffraction (XRD) patterns revealed the presence of CuO, Sb2O3 and Sb2O4phases. The absorption coefficient of Cu-Sb-O thin films in all cases is in the range104 -105 cm -1. The films after annealing have two direct band gap energies in the ranges 1.48,1.50 eV and 2.20-2.95 eV. The electrical measurements show a conversion from a metallic phase to the semiconductor phase after annealing. The samples exhibit p-type conductivity after annealing in air of the intermetallic multilayer systems (Cu/Sb)j=3 and (Sb/Cu)j=3. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Temperature-tuned band gap energy and oscillator parameters of Tl2InGaSe4 semiconducting layered single crystals

A theoretical investigation of ZnOxS1,x alloy band structure

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 5 2007
H. Rozale
Abstract We report the properties of ordered ZnOxS1,x alloys calculated in various structures (CuAu,I, Cu3Au, Luzonite and Famatinite) using a first-principles total-energy formalism based on the hybrid full-potential augmented plane-wave plus local orbitals (APW + lo) method, within the local-density approximation (LDA). The calculated band gaps of the alloys are direct and range from 0.49 for O-rich to 1.55 eV for S-rich ZnOxS1,x. The non linear variation of the band gap energy is related to the large electronegativity difference between O and S. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Ab initio modeling of small diameter silicon nanowires

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2006
Murat Durandurdu
Abstract Using ab initio calculations, we predict stable small diameter silicon nanowires. The wires are constructed from the expended phases of silicon, clathrate Si(34) and Si(46) structures, and found to be energetically more favorable than the diamond type nanowires at the same diameters. Furthermore, the wires are semiconducting with band gap energy of 0.22 eV and 0.34 eV. Chemical passivation of the wires with hydrogen induces a broadening of band gap energy due to the quantum size effect and increases the hardness of the wires. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Temperature shift of the Fe2+ absorption band in LiNbO3:Fe crystal

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 13 2004
M. H. Yükselici
Abstract The temperature dependence of the Fe2+ absorption band of a strongly oxidized LiNbO3:Fe crystal is reported over the range from 25 to 350 °C, where the effect of temperature on the band is reversible. The band broadens and shifts to lower energy as temperature is increased. The rate at which the absorption peak energy decreases with increasing temperature is calculated as ,6.8 × 10,5 eV/°C from the slope of the straight-line fit to the temperature against peak position energy graph. We propose that the origin of the temperature shift is due to both a shift of the energetic position of impurities and the decrease of the band gap energy. The consistency between the calculated rate by the help of a simplified model which describes the shift of the band gap energy in the frame of the lattice dilation and the observed rate suggests that the lattice dilation might be responsible for the temperature shift of the band. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Photoluminescence studies of isotopically enriched silicon

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 1 2003
D. Karaiskaj
Abstract We report the first high resolution photoluminescence studies of isotopically pure silicon. New information is obtained on isotopic effects on the indirect band gap energy, phonon energies, and phonon broadenings, which is in good agreement with previous results obtained in germanium and diamond. Remarkably, the line widths of the no-phonon boron and phosphorus bound exciton transitions in the 28Si sample (99.896% 28Si) are much sharper than in natural Si, revealing new fine structure in the boron bound exciton luminescence. Most surprisingly, the small splittings of the neutral acceptor ground state in natural Si are absent in the photoluminescence spectra of acceptor bound excitons in isotopically purified 28Si, demonstrating conclusively that they result from the randomness of the Si isotopic composition. [source]

Photoluminescence of cubic InN films on MgO (001) substrates

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008
T. Inoue
Abstract We have studied photoluminescence from cubic InN films grown on MgO substrates with a cubic GaN underlayer by RF N2 plasma molecular beam epitaxy. A single PL peak was observed at 0.47 eV. By analyzing the reflectance spectra of cubic InN films, we could derive the refractive index and extinction coefficient, and found the band gap energy of cubic InN is 0.48 eV, indicating that the PL peak observed at 0.47 eV is due to the interband transition of cubic InN. The difference in the PL peak energy between hexagonal and cubic InN is in good agreement with that predicted by ab-initio calculations. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Optical absorption and photoluminescence of CuAlTe2

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 8 2006
B. V. Korzun
Abstract The bulk crystals of the CuAlTe2 semiconductor ternary compound with the chalcopyrite structure were prepared, and their optical properties were investigated. It was determined that the value of band gap energy equals 1.69 and 1.65 eV at 105 and 293 K, respectively. The photoluminescence spectra were measured for the first time and contain broad bands with peaks at 1.09 eV (78 K) and 1.03 eV (293 K). The full width at half maximum (FWHM) for both temperatures is 0.28 eV. The origin of this band is associated with band to deep acceptor optical transition. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]