Photoelectric properties of InxGa1-xAs: A first-principles study

Abstract

The electronic structure and optical properties of the sphalerite structures InxGa1−xAs (x = 3.125%, 6.25%, 9.375%, 12.5%) were studied based on the first-principles method of density functional theory. The results demonstrate that the band-gap width of InxGa1−xAs decrease and the optical absorption frequency (absorption edge) emerges an obvious red-shift compared with GaAs due to the existence of impurity energy levels in the material. With the increase in Indium component ratio, the outer electronic hybridization degree of In and As decrease, and the band-gap width of InxGa1−xAs increases. As the component ratio of Indium increases from 6.25% to 9.375%, the band-gap magnitude increases from 0.55 eV to 0.63 eV. In terms of optical properties, the maximum peak values of the real and imaginary parts of dielectric function are 22.6 along [0 0 1] crystal direction and 25.71 along [1 0 0] crystal direction, respectively. The proportion of In component affects the material properties of crystal orientation and make the crystal gradually exhibit noticeable anisotropy. With increase in the proportion of In component, both the static dielectric constant of the material and the maximum peak of the refractive index decreases. In the region of higher energy, the reflection of the doped material is relatively weak for electromagnetic wave, and the average value of refractive index is around 0.7 with a high transmittance characteristic. The results show that the energy loss has a significant peak at the photon energy of 14.9 eV. Therefore, this calculation can provide a reference for the research and application of InGaAs optical detector.