AlGaN/GaN High Electron Mobility Transistor Grown and Fabricated on ZrTi Metallic Alloy Buffer Layers

AlGaN/GaN high electron mobility transistors (HEMTs) were demonstrated for structures grown on ZrTi metallic alloy buffer layers, which provided lattice matching of the in-plane lattice parameter ("a-parameter") to hexagonal GaN. The quality of the GaN buffer layer and HEMT structure were confirmed with X-ray 2 theta and rocking scans as well as cross-section transmission electron microscopy (TEM) images. The X-ray 2 theta scans showed full widths at half maximum (FWHM) of 0.06 degrees, 0.05 degrees and 0.08 degrees for ZrTi alloy, GaN buffer layer, and the entire HEMT structure, respectively. TEM of the lower section of the HEMT structure containing the GaN buffer layer and the AlN/ZrTi/AlN stack on the Si substrate showed that it was important to grow AlN on the top of ZrTi prior to growing the GaN buffer layer. The estimated threading dislocation (TD) density in the GaN channel layer of the HEMT structure was in the 10(8) cm(-2) range. (c) The Author(s) 2017. Published by ECS. All rights reserved.