First-principles study of the effects of doping B, N, and O on the photoelectric properties of Cr adsorbed GaS.

Context: To lessen the impact of the dangerous metal Cr, this paper applies the first principles to investigate the adsorption behavior and photoelectric properties of GaS on Cr. The effects of doped GaS on Cr adsorption behavior are investigated with four GaS systems, which are pure, boron (B)-doped, nitrogen (N)-doped, and oxygen (O)-doped, in order to maximize the characteristics of GaS for use in novel sectors, to obtain understanding of the impact of doping on the electronic structure and optical properties of GaS adsorption of Cr, as well as to promote the development of the material. Four GaS adsorbed Cr systems, pure, B-doped, N-doped, and O-doped, are optimized, and the optimized results show that the stable adsorption position of Cr on both pure and doped GaS is the top position of Ga atoms, whereas doped elements B, N, and O can promote the adsorption of Cr on GaS, and the order of the strength of this promotion is B > N > O.

Method: In this paper, molecular simulation calculations and analyses using the CASTEP module in the software Materials Studio are performed to simulate the structure optimization of GaS-adsorbed Cr materials doped with B, N, and O atoms by using the generalized gradient approximation (GGA) plane-wave pseudopotential approach [1] and the Perdew-Burke-Ernzerhof (PBE) generalized function [2]. From the convergence test, it is reasonable to set the K-point network to 4 × 4 × 1 and the truncation energy to 500 eV [3]. In this paper, a 3 × 3 × 1 supercell structure with 18 S atoms and 18 Ga atoms is selected. The convergence value of the iterative accuracy is 1.0e - 5 eV/atom, and all the atomic forces are less than 0.02 eV/Å. A vacuum layer of 16 Å is also set in the C direction to avoid interlayer interactions of GaS. First, we optimize the geometry of the model and then analyze the nature of the adsorption energy and electronic structure corresponding to the model.