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