Patent ID: 8309987
Filing Date: 2012-11-13
Classification: H01L

Abstract:
1. A semiconductor device comprising: a first active layer on a substrate; a second active layer on the first active layer, the second active layer having a higher bandgap than the first active layer, being substantially free of Ga and comprising at least Al; a two-dimensional electron gas (2-DEG) layer being present, in operation, on at least part of an interface between the first active layer and the second active layer; a gate insulating layer on at least a part of the second active layer; a gate electrode on at least a part of the gate insulating layer; and a source electrode and drain electrode on the second active layer, wherein the gate insulating layer is a thermal oxide formed by thermal oxidation of at least a part of the second active layer at a temperature between 500° C. and 1000° C., thereby consuming the top part of the second active layer and reducing the thickness of the second active layer so that the 2DEG is locally depleted.