RISS 검색 - 국내학술지논문

1
Effect of Isomorphic Atom Substitution on the Lattice Parameters and the Optical Absorption Edge of TlGaSe2-TlInSe2 Mixed Crystals

N. M. Gasanly 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.48 No.5I
The variation of lattice parameters of TlGaSe2-TlInSe2 mixed crystals with composition have been investigated by using of X-ray diffraction technique. For the mixed crystals studied, a structural phase transition (monoclinic to tetragonal) due to atom substitution is observed when the sum of the tetrahedral covalent radii of the Ga(In) and the Se atoms in Ga(In)Se4 tetrahedra reaches a critical value of about 0.254 nm. From transmission and reflection measurements, the compositional dependence of the indirect energy band gap was revealed.
2
Coexistence of Indirect and Direct Optical Transitions, Refractive Indices, and Oscillator Parameters in TlGaS2, TlGaSe2, and TlInS2 Layered Single Crystals

N. M. Gasanly 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.1
The optical properties of TlGaS2, TlGaSe2, and TlInS2 crystals have been investigated through transmission and reflection measurements in the wavelength range of 400 - 1100 nm. Optical indirect and direct band gap energies of 2.45 and 2.63 eV (TlGaS2), 1.97 and 2.26 eV (TlGaSe2), 2.27 and 2.47 eV (TlInS2) were found by analyzing the absorption data at room temperature. The transmission measurements carried out in the temperature range of 10 - 300 K revealed that the rates of change of the indirect band gaps with temperature were γ = -5.3 × 10−4, -4.2 × 10−4, and -9.2 × 10−4 eV/K for the TlGaS2, TlGaSe2, and TlInS2 crystals, respectively. The dispersion of the refractive index is discussed in terms of the single oscillator model. The refractive indices, the oscillator and dispersion energies, and the zero-frequency dielectric constants were determined.
3
Properties of Tl4Se3S single crystals and characterization of Ag/Tl4Se3S Schottky barrier diodes

A.F. Qasrawi,N.M. Gasanly 한국물리학회 2010 Current Applied Physics Vol.10 No.2
The main physical properties of Tl4Se3S single crystals were investigated for the first time. Particularly,the crystal data, Debye temperature, dark electrical resistivity and Hall effect in addition to the temperature dependent current–voltage characteristics and photosensitivity of the Ag/Tl4Se3S Schottky barrier diode were studied. The X-ray diffraction patterns have revealed that the crystal exhibited a single phase of tetragonal structure belonging to the D184h - I4mcm space group. A Debye temperature of 100 K was calculated using the results of the X-ray diffraction analysis. The dark electrical resistivity and Hall-effect measurements indicated that the samples exhibits p-type conduction with an electrical resistivity, carrier concentration and Hall mobility of 6.20 × 103 Ωcm, 1.16 × 1012 cm-3 and 873 ㎠ V-1 s-1, respectively. The crystals were observed to have Schottky diode properties. The Ag/Tl4Se3S Schottky barrier device bias voltage was observed to depend on the crystal direction and on temperature. It was found that the calculated energy barrier height decreased and the diode ideality factor increased with temperature decreasing. The photosensitivity–light intensity dependence of this device was found to be linear reflecting the ability of using it in optoelectronics.
4
Donor-Acceptor Pair Recombination in Tl2InGaS4 Layered Crystals

K. Goksen,A. Aydinli,H. Ozkan,N. M. Gasanly 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.47 No.1
Photoluminescence (PL) spectra of Tl2InGaS4 layered single crystals were studied in the temperaturerange 15 – 150 K and wide laser excitation intensity range 0.01 – 110.34 Wcm−2. We observed a total of three PL bands, one centered at 542 nm (2.286 eV, A-band), one at 607 nm (2.041 eV,B-band), and one at 707 nm (1.754 eV, C-band), at various excitation intensities. The A- and the B-bands were determined to be due to radiative transitions from moderately deep donor levels located at 0.189 and 0.443 eV below the bottom of the conduction band to the shallow acceptor levels at 0.025 and 0.016 eV above the top of the valence band, respectively. The blue shift of the C-band peak energy and the quenching of the PL with increasing temperature are explained within the configuration coordinate model. The observation in the PL spectra of different emission bands in the sequence of B-, C- and A-bands at low, moderate, and high excitation laser intensities,respectively, are attributed to the shift of the quasi-Fermi level with increasing excitation intensity.

상세검색

RISS 보유자료

상세검색

해외전자자료

연관 검색어 추천