Normally-off gallium nitride-based semiconductor devices

摘要

A method includes forming a relaxed layer in a semiconductor device. The method also includes forming a tensile layer over the relaxed layer, where the tensile layer has tensile stress. The method further includes forming a compressive layer over the relaxed layer, where the compressive layer has compressive stress. The compressive layer has a piezoelectric polarization that is approximately equal to or greater than a spontaneous polarization in the relaxed, tensile, and compressive layers. The piezoelectric polarization in the compressive layer could be in an opposite direction than the spontaneous polarization in the compressive layer. The relaxed layer could include gallium nitride, the tensile layer could include aluminum gallium nitride, and the compressive layer could include aluminum indium gallium nitride.

主权项

1. An apparatus comprising:
a relaxed layer over a semiconductor substrate; a tensile layer over the relaxed layer, the tensile layer having tensile stress; a compressive layer over the relaxed layer, the compressive layer having compressive stress; source and drain regions in at least the tensile layer; and a gate over the compressive layer; wherein the compressive layer has a piezoelectric polarization that is approximately equal to or greater than a spontaneous polarization in the relaxed, tensile, and compressive layers and wherein the tensile layer is next to the compressive layer.