Modeling of hot-carrier degradation in GaN transistors

Hot-electron effects play an important role in degradation of GaN high-electron-mobility transistors. The modeling approach presented here includes device simulation and atomic-scale defect description using density function theory (DFT). Hot electrons are generated by high electric fields in semiconductor devices. These energetic electrons can induce or modify defects that affect the device operation. Several degradation mechanisms of GaN-based high-electron mobility transistors (HEMTs) have been described recently in the literature. Experiments show that a variety of defects appear during device operation, but the connection between atomic-scale mechanisms and the degradation rate is difficult to establish. For example, the atomic-scale nature of the traps that produce changes in threshold voltage, leakage current, and drain current is not well known.