FIELD EFFECT TRANSISTOR

摘要

Disclosed is a field effect transistor comprising a semiconductor layer structure including a GaN channel layer (12) and an AlGaN electron supply layer (13), a source electrode (1) and a drain electrode (3) which are so formed on the electron supply layer (13) as to be separated from each other, a gate electrode (2) formed between the source electrode (1) and the drain electrode (3), and an SiON film (23) formed on the electron supply layer (13). The gate electrode (2) has a filed plate portion (5) projecting toward the drain electrode (3) side like an eave on the SiON film (23). The thickness of a portion (a field plate layer (23a)) of the SiON film (23) lying between the filed plate portion (5) and the electron supply layer (13) gradually increases from the gate electrode (2) side to the drain electrode (3) side.