US Patent 9099351 Compound semiconductor device and method of manufacturing the same

A compound semiconductor device includes as compound semiconductor layers: a first layer; a second layer larger in band gap than the first layer, formed above the first layer; a third layer having a p-type conductivity type, formed above the second layer; a gate electrode formed above the second layer via the third layer; a fourth layer larger in band gap than the second layer, formed to be in contact with the third layer above the second layer; and a fifth layer smaller in band gap than the fourth layer, formed to be in contact with the third layer above the fourth layer.