Variation of band gap energy and photoluminescence characteristics with Te composition of ZnS1−xTex epilayers grown by hot-wall epitaxy

ZnS1−xTex ternary alloy epilayers were grown on GaAs (1 0 0) substrates by hot-wall epitaxy (HWE), and the dependence of their band gap energy and photoluminescence (PL) characteristics on the Te composition x was investigated. The spectrophotometer measurement results demonstrated that the room temperature band gap energy varied with the Te composition x. The band gap energy showed the strong bowing effect given by Eg(x)=3.73−5.27x+3.80x2. The PL peaks of ZnS1−xTex epilayers shifted to the lower energy with increasing Te composition x. For x>0.69, the PL peak energy was very close to the band gap energy. Bowing parameter, 3.80, was closer to the value of Bernard et al., 3.83, and was a little larger than the previous other results. Strong emission ranging from blue to yellow was observed at room temperature. Also, the relations between Ten (n=1,2,3) atoms of the ZnS1−xTex epilayers and the exciton emission at room temperature were investigated.