Tunable Schottky barrier of GaSe/graphene heterostructure via asymmetric O doping

Abstract

Lowering the Schottky barrier remains a crucial challenge for enhancing charge transport and electrical performance of field-effect transistors based on heterostructures (HTSs). Using first-principles methods, we investigated how asymmetric O doping modifies the structural integrity and electronic properties of GaSe_(1−x)O_x/GR HTSs. The results demonstrate that graphene and GaSe_(1−x)O_x monolayers can form a stable van der Waals HTS. By modulating the concentration and position of interfacial O doping, the Schottky barrier height and interface contact type can be effectively modulated. Furthermore, the results show that when O is doped either inside or outside the interface, the Schottky barrier height gradually decreases as the doping concentration increases. Notably, when the concentration of the O dopant inside the interface reaches 50%, a conversion from an n-type Schottky contact to an Ohmic contact can be achieved, enabling high-efficiency charge transport. It has been conclusively verified that interfacial electron transfer increases steadily with increasing O dopant concentration at the interface, causing the Fermi level to shift toward the conduction band minimum of GaSe_(1−x)O_x, thereby reducing the Schottky barrier. These findings provide a feasible strategy for enhancing the electronic performance of GaSe/GR nanoscale field-effect transistors by asymmetric O doping.