Role of silicon on the conductivity GaSb surface: A first-principles study

Gallium antimonide (GaSb) has exceptional semiconductor properties, making it a promising material for various applications, leading to extensive theoretical and experimental studies. The prevalence of Ga-Sb antisite defects in unintentionally doped GaSb leads to intrinsic p-type conductivity, placing a limitation on its utility. Introducing dopants as electron donors to compensate for the vacancies induced by Ga-Sb antisite is viewed as a feasible strategy to ameliorate this issue. This study explores the transformation and enhancement of GaSb conductivity by analyzing the mechanism of Si doping using first-principles calculations. The calculated results show, the GaSb(001) surface with Ga-Sb antisite exhibits unintentional p-type conductivity. When Si as a dopant source, GaSb-3SiGa complex exhibits n-type conductivity. The pure GaSb(001) surface exhibits intrinsic conductivity, and when Si atoms are doped into the system, it only exhibits n-type conductivity. Taken together, the above observations suggest that Si, as an amphoteric dopant, can serve as an n-type dopant for GaSb. Additionally, the upward shift of the Fermi level upon the incorporation of Si atoms exhibits a consistent trend, irrespective of the presence of the Ga-Sb antisite. Furthermore, charge analysis indicates that the conduction band electron count increases, resulting in an improvement of conductivity. This study opens a new avenue for the preparation of potential high-performance GaSb-based semiconductor devices.