Improved carrier mobility of InAlN/GaN heterostructure grown on cone-shaped patterned sapphire substrate

Abstract

InAlN/GaN heterostructures were grown on both patterned and planar sapphire substrates by metal–organic chemical vapor deposition. Hall measurements showed that both samples possessed similar two-dimensional electron gas densities, whereas the electron mobility of the heterostructure grown on a patterned substrate was evidently superior. The enhanced mobility was attributed to the reduced threading dislocation density and improved channel-barrier interface morphology. Furthermore, Raman measurement results showed that there was less residual compressive strain in the GaN grown on the pattered sapphire substrate, which could be the reason for the morphology improvement. Consequently, the patterned sapphire substrate is very promising for further improving the performance of high-electron-mobility transistors.