Patent ID: 9337326
Filing Date: 2016-05-10
CPC Classification: H01L,H03F

Claim Text:
1. A compound semiconductor device comprising: a first electrode; a compound semiconductor layer which is formed above the first electrode and includes an opening; a second electrode formed above the compound semiconductor layer; and a gate electrode embedded in the opening lined with an insulating film; wherein the compound semiconductor layer comprises: a first compound semiconductor; a second compound semiconductor formed on the first compound semiconductor; a third compound semiconductor formed on the second compound semiconductor; and a fourth compound semiconductor in contact with a side surface of the insulating film, a side surface of the first compound semiconductor, a side surface of the second compound semiconductor, and a side surface of the third compound semiconductor, wherein a region where the fourth compound semiconductor does not exist is formed directly below the gate electrode, and a two-dimensional electron gas is produced at an interface of the first compound semiconductor with the fourth compound semiconductor and at an interface of the third compound semiconductor with the fourth compound semiconductor.