Abstract: A semiconductor device includes a barrier region and a channel region, source and drain electrodes, and a gate structure that is configured to control a conductive connection between the source and drain electrodes, wherein the barrier region comprises a first barrier layer and a second barrier layer, wherein in a central portion of the device the second barrier layer is the only layer that is disposed over the channel region, wherein in outer lateral portions of the device the first barrier layer is disposed over the channel region, wherein the first and second barrier layers are each III-V semiconductor alloys, and wherein a molar fraction of a second type III element in the central portion is higher than a molar fraction of the second type III element in the first barrier layer.

Abstract: A semiconductor device includes a semiconductor substrate including a barrier region, a channel layer disposed below the barrier region and forming a heterojunction with the barrier region such that a two-dimensional charge carrier gas channel is disposed in the channel layer near the heterojunction, and a sub-channel region disposed below the channel layer, and a first interface in the semiconductor substrate between a first region of type III-V material and a second region of type III-V material that is disposed below the first region of type III-V material, wherein the first and second regions of type III-V material form polarization charges on either side of the first interface, wherein the first interface is within or formed by the sub-channel region, and wherein semiconductor substrate has a vertically varying dopant concentration of deep energy acceptor dopant atoms that is locally increased at the first interface.

Abstract: A semiconductor device includes a semiconductor substrate including a barrier region, a channel layer disposed below the barrier region and forming a heterojunction with the barrier region such that a two-dimensional charge carrier gas channel is disposed in the channel layer near the heterojunction, and a sub-channel region disposed below the channel layer, and a first interface in the semiconductor substrate between a first region of type III-V material and a second region of type III-V material that is disposed below the first region of type III-V material, wherein the first and second regions of type III-V material form polarization charges on either side of the first interface, wherein the first interface is within or formed by the sub-channel region, and wherein semiconductor substrate has a vertically varying dopant concentration of deep energy acceptor dopant atoms that is locally increased at the first interface.