Density functional investigations to study effect of M = (Ge, Sn) doping on opto-electronic response of ZnSi(1-x)MxP2

Researchers have shown ample concern in the investigation of new potential materials which resembles with required band gap range for photovoltaic applications and hence demonstrates higher conversion rates when exposed to sunlight. Present study is focused towards identifying the effect of M = (Ge, Sn) doping on structural, electronic and optical properties of promising photovoltaic ZnSiP2 material. All Investigations have been performed using well-established and most precise full potential linearized augmented plane wave method. Detailed realization of pure and doped ZnSi(1 - x)MxP2 (M = Ge and Sn; 0 <= x <= 1) have been implemented using highly immaculate Tran-Blaha modified Becke-Johnson (TB-mBJ) exchange and correlation potential. Investigated parameters includes crystal structure, energy bands, density of states, dielectric tensor, absorption, reflectivity and refraction spectra which helps to elaborate complete behavior of these compounds. Energy band gap, attained from TB-mBJ, for pure ZnSiP2 (1.98 eV) matches precisely with available theoretical and experimental calculations and hence validates accuracy of present computation. This is observed that increase in doping percentage (x = 0.125 to 0.75) of Sn at Si site, results with systematic reduction in band gap (1.96 to 1.81 eV) value which increases possible utilization of this material in photovoltaic applications. On the other hand, reasonable reduction is not observed with Ge doping of similar scale.