Heterojunction field effect transistor having an improved transistor characteristic.

摘要

A field effect transistor (20) comprises a first semiconductor layer (24) and a second semiconductor layer (25) formed on the first semiconductor layer. The first semiconductor layer is an undoped layer and is composed of InGaAs. The second semiconductor layer is composed of InAlGaP and is a doped layer in which an n-type impurity is doped. A heterojunction structure is formed between the first semiconductor layer and the second semiconductor layer.