A Theoretical Approach to the Optical Gaps of 1D- and 3D-Se_<1-x>Te_x

概要

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To stud)' the relation between the interchain and intrachain interactions as well asto compare the chain-like features with the bulk characteristics in chalcogenidealloys, the Te concentration (,v) dependence of the optical gap E. is theoreticallyanalyzed for Se.-,Te.. of an isolated chain and a trigonal crystal. In the first place,band structures are calculated for an isolated chain and for a trigonal crystal by thetight-binding approximation. The behaviour of the interaction parameters obtainedfrom our calculations indicates that the chain-like nature of a trigonal crystalbecomes less distinguished as the increase of x. Secondly, the electronic density ofstates of Se. ,Te. is calculated by the coherent potential approximation. The resultsshow that the optical gap E. for a bulk mixture decreases as x increases while E. for achain does not change very much for x>0.2. These results are in good agreement withthe experimental data.[selenium-tellurium mixture, optical gap, tight-binding theory, coherent poten- ][ tial approximation, one- and three-dimensional crystalI
社団法人日本物理学会の論文
1992-04-15