Ab-initio Study of the Optoelectronic Properties of a Semiconductor Under the Influence of an External Electric Field: The Case of Silicon (Si)

DFT calculations are performed on the structural, electronic, and optical properties of fcc silicon (Si). The plane wave (PW) method using Perdew-Burke-Ernzerhof generalized gradient approximation (PBE-GGA) exchange correlation potentials is applied to solve the Kohn-Sham equations. Energy convergence was examined to study ground-state properties. Band structure and total density of states (TDOS) diagrams are plotted from the calculated equilibrium lattice parameters. An electric field on the order of E=0 V/Å and E= 1V/Å is applied to the silicon surface. Band structure and energy density of Si at electric field E=0 V/A and E= 1V/A is studied in this paper. We also studied variation of the Fermi energy of Si as a function of the applied electric field. On simulate real part of the dielectric function ɛ1(ω) and Imaginary part of the dielectric function ɛ2(ω) as a function of the photon energy for Si with electric field E=0 V/Å and E= 1V/Å (10 GV/m). General profiles of the optical spectra under ambient conditions with and without an electric field are calculated. This study shows that applying an electric field normal to the surface of silicon modifies its electronic and optical properties. The band gap of silicon contracts, with the appearance of band degeneracy. The peak amplitude of its absorption coefficient, the dielectric function and the refractive index decrease in the ultraviolet range and increase in the visible range.