Investigations of modulation method and stress mechanism for the growth of AlGaN channel heterostructures.

In this work, the strong connection between the channel and the barrier layer of AlGaN channel heterostructures has been investigated in detail. Unlike GaN as a channel material, AlGaN channel layers significantly influence the transport characteristics and quality of AlGaN barrier layers with increasing Al composition. Furthermore, the stress mechanism in the growth of the AlGaN layer has been thoroughly discussed. It has been revealed that the modulation of the channel layer stress alters its relaxation and enhances the consistency of the in-plane lattice constant, thereby improving channel layer quality. Moreover, this process reduces the tensile stress on the barrier layer, and improves the barrier layer quality and heterostructures performance. This work is not only beneficial for the achievement of high breakdown voltage and new generations of high-power RF devices, but is also instructive to the optimization and realization of the AlGaN material in deep-UV devices.