Abstract
The high pressure band structure, density of states, metallization, structural phase transition and superconductivity of cubic zinc blende type zinc selenide (ZnSe) and cadmium selenide (CdSe) are investigated using the full potential linear muffin-tin orbital (FP-LMTO) method. The ground state properties and band gap values are compared with the experimental results. The equilibrium lattice constant, bulk modulus and its pressure derivetive and the phase transition pressure at which the compounds undergo structural phase transition from ZnS to NaCl are predicted from the total energy calculations. The density of states at the Fermi level (N(EF)) gets enhanced after metallization, which leads to the superconductivity in ZnSe and CdSe. The superconducting transition temperatures (Tc) of ZnSe and CdSe are obtained as a function of pressure for NaCl structure. ZnSe and CdSe come under the class of pressure induced superconductors. When pressure is increased Tc increases in both compounds. The dependence of Tc on electron - phonon mass enhancement factor λ shows that ZnSe and CdSe are electron-phonon-mediated superconductors.
Highlights
The physical properties of materials undergo a variety of changes when they are subjected to high pressure [1]
Even though we have obtained the band structure for V/Vo values from 1.0 to 0.3, we have presented here the band structures of zinc selenide (ZnSe) and cadmium selenide (CdSe) along the symmetry directions Γ-X-W-L-Γ-K corresponding to volume compressions V/Vo=1.0 and V/Vo=0.686 for ZnSe, and V/Vo=1.0 and V/Vo=0.6313 for CdSe only (Figs.1,3,5 and 7)
The ground state properties and structural phase transitions of ZnSe and CdSe are studied from their total energies obtained from our calculation
Summary
The physical properties of materials undergo a variety of changes when they are subjected to high pressure [1]. The increase of pressure means the significant decrease in volume, which results in the change of electronic states and crystal structure. With the development of high pressure experimental techniques, investigations on pressure-induced structural phase transition, semiconductor-metal transition and superconducting transition are getting the attention of all. II-VI compounds ZnSe and CdSe. One of the most important characteristics of semiconductor, which distinguish it from the metals and insulators, is its energy band gap. One of the most important characteristics of semiconductor, which distinguish it from the metals and insulators, is its energy band gap This property determines among other things, the wavelength of light which it can absorb or emit. Concentration of impurities or doping materials play important role to control the electronic and optical properties of semiconductors [1]
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