Performance of Fully Recessed AlGaN/GaN MOSFET Prepared on GaN Buffer Layer Grown With AlSiC Precoverage on Silicon Substrate

A crack-free AlGaN/GaN heterostrucure is grown on 4-in Si (111) substrate with AlSiC precoverage layer. Covering the Si surface with the AlSiC layer, until the growth of the AlN wetting buffer layer, is found to be effective in compensating the strong tensile stress in the GaN layer grown on Si substrate. The metal-oxide-semiconductor field-effect transistor, fabricated on this AlGaN/GaN heterostructure, exhibits excellent normally-off characteristics with threshold voltage of 7.2 V, maximum drain current of 120 mA/mm, ON/OFF current ratio of
${\sim}10^{8}$
, and subthreshold slope of 80 mV/decade.