Patent ID: 9099341
Filing Date: 2015-08-04
Classification: H01L

Abstract:
1. A field effect transistor comprising: a lower barrier layer which is placed on a substrate and which is made of Al a channel layer which is placed on a surface of the lower barrier layer that is opposite to the substrate and which is made of GaN; an upper barrier layer which is placed on a surface of the channel layer that is opposite to the lower barrier layer and which is made of Al a source electrode and drain electrode which are placed on a surface of the upper barrier layer that is opposite to the channel layer; an insulating layer placed on a region of the upper barrier layer, the region being in a surface of the upper barrier layer that is provided with the source electrode and the drain electrode, the region excluding a region provided with the source electrode and the drain electrode; a gate electrode placed on the insulating layer; and a region directly under the gate electrode having a recessed structure in which the insulating layer extends through the upper barrier layer and partly into the channel layer; wherein the channel layer includes a first channel sub-layer located on the upper barrier layer side and a second channel sub-layer located on the lower barrier layer side, the n-type doping concentration of the first channel sub-layer is less than the n-type doping concentration of the second channel sub-layer, and the insulating layer is placed so as not to reach the second channel sub-layer.