Electronic structures and optical properties of Culn_(1-x)Ga_xSe_2 by first-principle calculations

摘要

First-principle calculations on the electronic structures and optical properties of Culn_(1-x)Ga_xSe_2(x=0, 0.25, 0.5, 0.75 and 1) reveal that Culn_(1-x)Ga_xSe_2 are small band gap materials and the ground state is stabiles from x=0 to 1 while the band-gap of the quaternary compound widen, all of that are in good agreement with the experimental results. We find that the obviously double peak structure of the imaginary of dielectric function centered about from 0.9 to 5.0 while a distinct peak appears at about 2.2eV and a smooth increasing with another peak appearing at about 5.5eV for the different content of Ga appearing in the absorption spectrum, all of which indicate the different band gap for the transition.