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Title: An analysis of temperature-dependent absorption and photocurrent spectra in BaAl{sub 2}Se{sub 4} layers

The temperature-dependent photoresponse behavior of BaAl{sub 2}Se{sub 4} layers has been investigated through the analysis of optical absorption and photocurrent (PC) spectra. Based on these results, the optical band gap was well expressed by E{sub g}(T) = E{sub g}(0) − 4.39 × 10{sup −4}T{sup 2}/(T + 250), where E{sub g}(0) is estimated to be 3.4205, 3.6234, and 3.8388 eV for the transitions corresponding to the valence band states Γ{sub 3}(A), Γ{sub 4}(B), and Γ{sub 5}(C), respectively. From the PC measurement, three peaks A, B, and C corresponded with the intrinsic transitions from the valence band states of Γ{sub 3}(A), Γ{sub 4}(B), and Γ{sub 5}(C) to the conduction band state of Γ{sub 1}, respectively. According to the selection rule, the crystal field and spin orbit splitting were found to be 0.2029 and 0.2154 eV, respectively, through the direct use of PC spectroscopy. However, the PC intensities decreased with lowering temperature. In the log J{sub ph} versus 1/T plot, the dominant trap level at the high-temperature region was observed and its value was 12.7 meV. This level corresponds to the activation energy for the electronic transition from the shallow donor levels to the edge of the conduction band. It is estimated that the decrease in the PC intensity is caused by trapping centersmore » related to native defects in the BaAl{sub 2}Se{sub 4} layers. Consequently, this trap level limited the PC intensity with decreasing temperature.« less
Authors:
 [1] ; ;  [2] ;  [3]
  1. Department of Physics, Chosun University, Gwangju 501-759 (Korea, Republic of)
  2. School of Semiconductor and Chemical Engineering, Semiconductor Physics Research Center (SPRC), Chonbuk National University, Jeonju 561-756 (Korea, Republic of)
  3. Department of Electrical Engineering, Dongshin University, Naju 520-714 (Korea, Republic of)
Publication Date:
OSTI Identifier:
22402956
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 16; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABSORPTION; ABSORPTION SPECTROSCOPY; ACTIVATION ENERGY; ALUMINIUM SELENIDES; BARIUM COMPOUNDS; CRYSTAL FIELD; ELECTRONIC STRUCTURE; EV RANGE; LAYERS; SELECTION RULES; SPIN; TEMPERATURE DEPENDENCE; TRAPS; VALENCE