Studies on Spin Orbit Splitting and Dual Mode Phonon Vibrations in ZnSxSe1 x Ternary Alloys Films with Varying Se Concentration

Abstract

ZnSxSe1 x (x = 0, 0.41, 0.51, 0.91, 1) ternary alloy thin films with variable structural, optical and vibrational properties were prepared by thermal evaporation of solvothermally synthesized ZnS-ZnSe nanocomposite powders. The deposited films were uniform and have zinc-blende structure with (111) orientation. Variation of lattice parameter with composition was slightly nonlinear with a bowing parameter of 0.12 A ° . Spin orbit (SO) splitting of the valence band was observed in binary ZnSe and ternary samples with large Se atomic concentration such as ZnS0.41Se0.59 and ZnS0.51Se0.49. The SO splitting energy decreases as the Se atomic concentration in the alloy decreases. Two phonon modes (corresponding to ZnS and ZnSe bonds) behavior were observed in the Raman spectra of the ternary alloys. The observed phonon mode frequencies shifted with changes in Se atomic concentration in agreement with theroretical predictions. Gap mode vibration of Se in ZnS lattice was also observed at 221 cm 1 in the ternary sample with small Se atomic concentration (ZnS0.91Se0.09), which also matches closely with theoretically calculated values.