Thermodynamics and kinetics of vacancy self-compensation in wide-bandgap semiconductors

Thermodynamic and kinetic aspects of anion vacancy self-compensation of p-type layers in three compound semiconductors, namely GaN, ZnSe and SiC, are considered. Thermodynamic considerations indicate that SiC p-type layers are thermodynamically stable, whereas GaN and ZnSe p-type layers are thermodynamically unstable, with respect to anion-vacancy self-compensation. Hence, if GaN and ZnSe compound semiconductor devices with p-type layers are to exhibit long-term stability, it is important that kinetic barriers be established which preclude the supply of anion vacancies to the p-type layer. Kinetic strategies for minimizing anion-vacancy self-compensation include growing p-type layers free of grain boundaries and dislocations, placing the p-type layers remote from surfaces and embedding the p-type layer in heavily n-doped regions.