Theoretical Study On Defects And Surface Of Gallium Antimonide

Gallium antimonide（GaSb）has emerged as the primary material for high-performance mid-infrared lasers due to its excellent electron mobility and photo-electric conversion characteristics.However,its applications are restricted by the presence of a large number of acceptor defects.GaSb exhibits p-type conductivity in non-intentional doping conditions,mainly due to the abundance of antisite defects and V_Gavacancies,with the former being the direct cause of p-type conductivity.Whether silicon（Si）can be used as an n-type dopant for GaSb has been controversial.Recent experiments have shown that Si doping significantly improves the conductivity,but the underlying physical mechanism is still unclear.Understanding the electrical properties of Si-doped GaSb and the physical mechanisms leading to increased conductivity is of great scientific and practical significance in improving device performance and expanding application fields.In this study,first-principles calculations were used to investigate the effects of Si doping on the electrical properties of GaSb.The innovative findings include:1、The band gap value of the GaSb bulk was calculated using the DFT-1/2method,with a result of 0.79 e V,which is consistent with the experimental value.This demonstrates that the DFT-1/2 method has high computational accuracy and speed,indicating its significant value in calculating solid material properties.2、The reasons for the p-type conductivity in GaSb under non-intentional doping conditions were explained,primarily due to the abundance of antisite and V_Gadefects,with the former being the most direct cause of p-type conductivity.Further surface analyses indicated that Si tends to distribute near the surface of GaSb,which agreed with the experimental results.3、The n-type conductivity mechanism of Si-doped GaSb was revealed.The results showed that the Ga_Sb-3Si_Gacomplex exhibited n-type conductivity.Pure GaSb（001）surfaces exhibit intrinsic conductivity,and when Si atoms are doped,only n-type conductivity is shown.Regardless of the presence of GaSb antisite defects,Fermi level displays a consistent upward trend when Si atoms are doped.Additionally,charge analysis showed that an increase in the number of conduction electrons in the conduction band led to increased conductivity.This study clarified the effects of Si doping on the electrical properties of GaSb at the atomic and electronic scale,revealing the physical mechanisms leading to increased conductivity.These findings provide theoretical guidance for the design of GaSb-based semiconductors.