Patent ID: 8829568

Claim:
A gallium nitride semiconductor device comprising: a first semiconductor layer containing gallium nitride; a second semiconductor layer containing gallium nitride and formed on part of a surface of the first semiconductor layer; a first semiconductor element formed in the first and second semiconductor layers and having a high withstand voltage; and a second semiconductor element formed in either the first or the second semiconductor layer and having a low withstand voltage, wherein the first semiconductor layer has an insulating region provided between the first and second semiconductor elements for separating the first and second semiconductor elements from each other, wherein the first semiconductor element uses the second semiconductor layer as a drift region, and further comprises a second conductivity type first source region formed on a surface layer of the first semiconductor layer where the second semiconductor layer is not formed, wherein the second semiconductor element further has a high concentration first conductivity type third semiconductor layer formed on a surface of the second semiconductor layer, wherein the second semiconductor element is formed from a first conductivity type insulated gate field effect transistor and a second conductivity type insulated gate field effect transistor, wherein the first conductivity type insulated gate field effect transistor has a second source region and a first drain region on a surface of the first semiconductor layer, and wherein the second conductivity type insulated gate field effect transistor uses the third semiconductor layer as a third source region and a second drain region.