An Overview of Gallium Nitride Substrate Materials Developments for Optoelectronic and Microelectronic Applications

 

A. D. Hanser1, L. Liu1, E. A. Preble1, D. Tsvetkov1, M. Tutor1, N. M. Williams1, K. Evans1, Y. Zhou2,

D. Wang2, C. Ahyi2, C.-C. Tin2, J. Williams2, M. Park2, D. F. Storm3, D. S. Katzer3, S. C. Binari3,

J.A. Roussos3, and J.A. Mittereder3

 

1Kyma Technologies, Inc. 8829 Midway West Road, Raleigh, NC 27617 (919) 789-8880 hanser@kymatech.com

2Department of Physics, Auburn University, Auburn, AL 36849

3 Electronics Science & Technology Division, US Naval Research Laboratory, 4555 Overlook Ave. S.W.,

Washington, D.C. 20375

 

Keywords: GaN, bulk substrates, HVPE, FET, Schottky diode

 

 

Abstract

     The hydride vapor phase epitaxy technique has been used to grow bulk GaN crystals for processing into free-standing substrates for optoelectronic and micro-electronic applications.  Substrates up to 2 inches in diameter were fabricated and tested for materials properties and device applications. Defect densities as low as 5x104 cm-2 were measured via CL imaging.  Semi-insulating electrical behavior was achieved through Fe doping with room temperature resistivity measurements as high as 2×109 Ω·cm measured using COREMA. Schottky diodes with >600V breakdown voltage and 20 ns reverse recovery time were fabricated. AlGaN/GaN HEMTs were fabricated and tested, resulting in an output power density of 5.0 W/mm at 2 GHz with a power- added efficiency of 35% and an associated gain of 14.5 dB. This constitutes the first report of significant power density from MBE-grown HEMTs on free-standing HVPE GaN substrates.

 

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