Gate-drain capacitance and conductance measurements were performed on an Al 0.15 Ga 0.85 N/GaN heterostructure field-effect transistor to study the effects of trap states on frequency-dependent device characteristics. By varying the measurement frequency in addition to the bias applied to the gate, the density and time constants of the trap states have been determined as functions of gate bias. Detailed analysis of the frequency-dependent capacitance and conductance data was performed assuming models in which traps are present at the heterojunction ͑interface traps͒, in the AlGaN barrier layer ͑bulk traps͒, and at the gate contact ͑metal-semiconductor traps͒. Bias-dependent measurements were performed at voltages in the vicinity of the transistor threshold voltage, yielding time constants on the order of 1 s and trap densities of approximately 10 12 cm Ϫ2 eV Ϫ1 .
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.