AlGaN/GaN-heterostructures on (111) 3C-SiC/Si pseudo substrates for high frequency applications

Abstract

We present the realization of high electron mobility transistors (HEMTs) based on AlGaN/GaN heterostructures, which were grown on silicon substrates using an ultrathin SiC transition layer. The growth of AlGaN/GaN heterostructures on 3C-SiC(111)/Si(111) was performed using metalorganic chemical vapour deposition (MOCVD). The 3C-SiC(111) transition layer was realized by low pressure CVD and prevented Ga-induced meltback etching and Si-outdiffusion in the subsequent MOCVD growth. The two-dimensional electron gas (2DEG) formed at the AlGaN/GaN interface showed an electron sheet density of 1.5 × 10 13 cm − 3 and a mobility of 870 cm 2/Vs. The HEMTs DC and RF characteristics were analysed and showed a peak cut-off frequency as high as 29 GHz for a 250 nm gate length.