Suppression of Current Collapse of High-Voltage AlGaN/GaN HFETs on Si Substrates by Utilizing a Graded Field-Plate Structure

Current collapse of AlGaN/GaN heterostructure field-effect transistors (HFETs) formed on qualified epitaxial layers on Si substrates was successfully suppressed using graded field-plate (FP) structures. To improve the reproducibility of the FP structure manufacturing process, a simple process for linearly graded SiO2 profile formation was developed. An HFET with a graded FP structure exhibited a significant decrease in an on-resistance increase ratio of 1.16 even after application of a drain bias of 600V.