Structural and electronic properties of Y_1-xGe_xTe (Y=Sn,Pb) by DFT

The structural, electronic, and chemical bonding properties of the Ge doped PbTe and SnTe in the rock salt phase have been calculated by full potential linearized augmented plane wave method within density functional theory. Generalized gradient approximation of Wu and Cohen has been utilized for calculating these properties. With doping of Ge in Pb_1-xGe_xTe and Sn_1-xGe_xTe, the lattice constant reduces linearly as the concentration increases. Also, it is observed that electronic properties of these compounds are affected by varying concentration of doping Ge. The band gap of corresponding compounds varies with respect to the composition, so the electronic properties alter as doping increases. The alloys have direct band gap which varies in the range 0 to 0.19 eV. The alloys Pb_1-xGe_xTe and Sn_1-xSn_x Te show covalent bonding nature which enhances by increasing the Ge concentration. As the physical properties vary widely with doping therefore the resulted materials can be used in thermoelectric, optical storage devices, Infrared detectors, Bragg's reflectors and optical devices working in lower frequency regime.