Heterojunction field-effect transistor

摘要

A heterojunction field-effect transistor having a high breakdown voltage and a low series resistance during operation suitable for use in microwave and millimeter-wave band oscillators and power amplifiers is provided. The heterojunction field-effect transistor has a gate recess structure and includes a gate electrode, a barrier layer, a contact layer, and a recess layer formed between the barrier layer and the contact layer. The recess layer is constituted from a plurality of recess sublayers, and the carrier density of the lowermost sublayer of the recess sublayers is 1/3 to 3 times the carrier density of the other recess sublayers.