Enhanced mobility for MOCVD grown AlGaN/GaN HEMTs on Si substrate

Growth and optimization of AlGaN/GaN transistors on Si substrate is an important subject of investigation to surpass the cost effective substrates like GaN, SiC and sapphire. In the ongoing study of GaN devices on Si, we have achieved record high room temperature mobility (μ_RT) of 3215 cm²/Vs for AlGaN/GaN HEMTs grown by MOCVD. Our approach to increase the mobility involves (i) reducing dislocation density by using thick buffer on Si and (ii) using 1.5 nm AlN spacer. This is the highest μ_RT so far reported for AlGaN/GaN grown on GaN, SiC and sapphire substrates. The growth and device characteristics of these HEMTs which have high mobility are presented in this report.