Patent ID: 8716755

Claim:
A semiconductor device comprising: a buffer layer made of a nitride semiconductor; a channel layer formed over the buffer layer and made of a nitride semiconductor formed over the buffer layer; a barrier layer formed over the channel layer and made of a nitride semiconductor; a cap layer formed over the barrier layer and made of a nitride semiconductor; a gate insulating film formed so as to be in contact with the cap layer; and a gate electrode formed over the gate insulating film, wherein compression strains are generated at an interface between the cap layer and the barrier layer and an interface between the channel layer and the buffer layer; wherein a tensile strain is generated at an interface between the barrier layer and the channel layer; wherein the channel layer has a stacked layer structure of a first layer, a second layer, and a third layer; and wherein the second layer has a higher electron affinity than those of the first layer and the third layer.