Pendeo-Epitaxy Process Optimization of GaN for Novel Devices Applications

Report No. ARL-TR-4426
Authors: Michael A. Derenge, Tsvetanka S. Zheleva, Kenneth A. Jones, Pankaj B. Shah, Daniel Ewing, J. Molstad, Unchul Lee, Matthew H. Ervin,and David N. Stepp
Date/Pages: April 2008; 22 pages
Abstract: A relatively new class of materials known as wide bandgap materials and the corresponding devices fabricated from them have extremely useful characteristics for hightemperature, high-frequency, high-power applications in numerous army systems and components. However the technology for these new materials is not mature enough and these materials contain various types of structural defects in high concentrations. It is well known that structural defects degrade the performance of the electronic devices and greatly diminish their reliability. Therefore various approaches for materials and devices optimization have been utilized in order to improve the operational characteristics of the wide bandgap electronic devices. One approach for defect reduction and improved electronic performance of wide-bandgap devices fabricated from material such as gallium nitride (GaN) is via pendeo-epitaxy. Pendeo-epitaxy as a technology is known to enable drastic reduction of the densities of structural defects in GaN over three to four orders of magnitude. We have used metal organic chemical vapor deposition (MOCVD) technique to grow pendeo-epitaxial (PE)-GaN, performed analysis of the morphology, structure, and electrical properties via numerous characterization techniques available at ARL, and correlated the materials and electrical characteristics with the growth and processing conditions. Further, we designed and fabricated test device structures in order to investigate the improved electronic performance of the Shottky contacts and high electron mobility transistors (HEMTs) and correlate the improved devices performance with the improved structural quality of the GaN material.
Distribution: Approved for public release
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Last Update / Reviewed: April 1, 2008