Patent ID: 7923753
Filing Date: 2011-04-12
Classification: H01L

Abstract:
1. An Ohmic electrode structure, comprising: a substrate; an electron transit layer formed of a first semiconductor layer formed on a main face side of the substrate; an electron supply layer, forming a heterojunction with the electron transit layer at a hetero-interface, formed on the electron transit layer, the electron supply layer including a second semiconductor layer having electron affinity smaller than that of the first semiconductor layer; a two-dimensional electron layer having a two-dimensional electron gas, induced from the hetero-interface and extending into the electron transit layer; and an Ohmic electrode of a metal material disposed in a recess surrounded by side faces forming sidewalls of depression and a bottom face connecting lower ends of the side faces, said bottom face of said recess being disposed lower than the hetero-interface, one end portion of the Ohmic electrode on the main face side penetrating the electron supply layer from a top face of the electron supply layer and being positioned in said electron transit layer, at a depth equal to or greater than the hetero-interface, but not exceeding the depth of the electron transit layer, and, at a point where said Ohmic electrode contacts the hetero-interface, an angle on an acute-angle side made by a tangential plane of the surface of the Ohmic electrode with a plane of extension of the hetero-interface being greater than 0° and less than or equal to 56°.