Electronic structure and optical property of As₂(Te_1−xS_x)₃ and As₂(Te_1−xSe_x)₃ crystals

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• 作者：Ching-Hwa Ho^a ; ^b ; ^{chho@mail.ntust.edu.tw"" rel=""nofollow}
• 关键词：Arsenic chalcogenides ; Thermoreflectance
• 刊名：Journal of Alloys and Compounds
• 出版年：2011
• 出版时间：30 June 2011
• 年：2011
• 卷：509
• 期：26
• 页码：7198-7204
• 全文大小：882 K

文摘

Single crystals of S- and Se-incorporated As₂Te₃ have been grown by vertical Bridgman method. The electronic structure and optical property of As₂(Te_1−xS_x)₃ [ATS] and As₂(Te_1−xSe_x)₃ [ATSe] series compounds have been characterized experimentally by thermoreflectance (TR) measurements in a wide energy range of 0.7–6 eV. X-ray diffraction measurements showed that the diffraction peaks of sulfur- and selenium-incorporated As₂(Te_1−xS_x)₃ 0 ≤ x ≤ 0.3 and As₂(Te_1−xSe_x)₃ 0 ≤ x ≤ 0.6 crystals shift to higher diffraction angles with the increase of the sulfur or selenium incorporations. The analysis of X-ray measurement revealed similar crystalline phase for the As₂Te₃ and those of the S- or Se-incorporated As₂Te₃. The experimental TR spectra of As₂(Te_1−xS_x)₃ (0 ≤ x ≤ 1) and As₂(Te_1−xSe_x)₃ (0 ≤ x ≤ 1) exhibit a lot of derivative-like spectral features in the vicinity of band edge as well as in the higher-lying bands. Transition energies and broadening parameters of the TR features at 40 and 300 K were analyzed. Compositional dependences of band gap and interband transition energies of the ATS and ATSe series were evaluated. The origins for the interband transitions in the ATS and ATSe are assigned. Based on the experimental analyses, the electronic structure of the diarsenic trichalcogenides, As₂(Te_1−xSe_x)₃ and As₂(Te_1−xS_x)₃, is hence being realized.