Status of Structural Analysis of Substrates and Film Growth Inputs for GaN Device Development Program

Report No. ARL-TR-5427
Authors: Kevin Kirchner
Date/Pages: January 2011; 36 pages
Abstract: This report covers the x-ray diffraction crystallographic analysis of semiconductor wafers involved in our teams project to produce gallium nitride (GaN) wide bandgap devices. The wafers were examined for crystal quality by symmetric and asymmetric GaN scans for each quadrant of the 18 wafers. Data comparisons made include the figures of merit (FOM) for GaN substrates compared with those of GaN films grown on the substrates, and the homoepitaxial GaN films' FOMs compared with those from heteroepitaxial films. The analysis produced the best FOMs for GaN for our lab to date: 39 (arc seconds) symmetric and 58 asymmetric. The good homoepitaxial GaN film quality was ~3 to 8 times better than that of good heteroepitaxial films. The heteroepitaxial GaN film quality was shown to be suited for our experimental needs. At a 95% confidence level, we were able to show a bias between the quality of the wafer quadrants of the Hydride Vapor Phase epitaxially grown GaN substrates. The microstructural quality of the material inputs as measured by x-ray diffraction is currently on track to play its part in the development of novel GaN-based devices.
Distribution: Approved for public release
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Last Update / Reviewed: January 1, 2011