Investigation of the temperature-dependent photoconductive behaviors of hot-wall-deposited MnAl₂Se₄ layers

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• 作者：S. H. You ; K. J. Hong ; J. W. Jeong ; H. S. Park…
• 关键词：MnAl2Se4 ; Photocurrent ; Valence ; band splitting ; Bandgap ; Temperature dependence
• 刊名：Journal of the Korean Physical Society
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：70
• 期：2
• 页码：155-161
• 全文大小：
• 刊物主题：Physics, general; Theoretical, Mathematical and Computational Physics; Particle and Nuclear Physics;
• 出版者：The Korean Physical Society
• ISSN：1976-8524
• 卷排序：70

文摘

The photoconductive characterization of hot-wall-deposited MnAl₂Se₄ layers was investigated as a function of temperature. By measuring the photocurrent (PC) spectroscopy, we identified PC peaks corresponding to an intrinsic transition, i.e., a band-to-band transition. According to the selection rule, the crystal field and the spin-orbit splitting in the valence band were found to be 150.3 and 9.2 meV, respectively. With decreasing temperature, the position of the PC peak shifted toward the short wavelength region, and its variation was matched well by using E_g(T) = E_g(0) − 3.19 × 10−3 T2/(T + 488). E_g(0) was estimated to be 3.5616, 3.7119, and 3.7211 eV corresponding to E_g(A), E_g(B), and E_g(C) in the valence band in order of increasing energy, respectively. The PC intensity also decreased dramatically with decreasing temperature. From a semi-logarithmic plot of the PC density vs. the reciprocal temperature, the dominant trap level was extracted as 19.7 meV in the high-temperature region. Consequently, we found that trapping centers due to native defects in the MnAl₂Se₄ layers were responsible for the decrease in the PC intensity with decreasing temperature.