Ab Initio Calculations Of Elastic Constants And Phase Transition Of ZnSe å'Œ ZnS

As semiconductors, ZnSe and ZnS are the most suitable candidates for fabrication of photovoltaic devices, semiconductor lasers and light emitting diodes. Despite the technological developments of ZnSe, the high pressure behavior of ZnSe has been the subject of considerable attention. Many fundamental problems for ZnSe under high pressure condition, such as the structural, electronic and bonding mechanisms, still remain unsolved. Recently, properties of material at high pressures and high temperatures have been the objects of intensive experimental and theoretical investigations.Firstly, the transition phase of ZnSe from the ZB to the RS structure is investigated by ab initio plane-wave pseudopotential density functional theory, and the lattice constant a, the bulk modulus B₀ and the first order pressure derivative of bulk modulus B'₀ are obtained. According to the usual condition of equal enthalpies, we find that the transition from the ZB structure to the RS structure occurs at the pressure of 16.8 GPa, as is well consistent with the experimental data and other theoretical results.Secondly, the transition phase of ZnS from the ZB to the RS structures is also investigated. It is found that the transition from the ZB structure to the RS structure occurs at the pressure of 15.4 GPa, as is well consistent with the experimental data and other theoretical results.