Influence of Al pre-deposition time on AlGaN/GaN heterostructures grown on sapphire substrate by metal organic chemical vapor deposition

Abstract

Aluminum (Al) pre-deposition technology was employed to grow high-quality AlGaN/GaN heterostructures on c-plane sapphire substrates by metal organic chemical vapor deposition. The effects of Al pre-deposition time on the structural and transport properties of the heterostructures were investigated in detail. The optimal Al pre-deposition time was found to be 3 s, and the AlGaN/GaN heterostructures grown under the optimal conditions possessed the surface root mean square roughness of 0.312 nm, threading dislocation density of 1.66 × 109 cm−2, two-dimensional electron gas (2DEG) mobility of 1808.09 cm2/V s and wafer resistance non-uniformity of 0.65%. Further, the influence mechanism of Al pre-deposition time on the dislocation density in the GaN buffer layer was revealed through the research on bare AlN nucleation layer grown on sapphire substrates. The results in this work not only demonstrate the great potential of AlGaN/GaN heterostructures with Al pre-deposition technology in electronic device applications, but also provide practical guidance for the growth of high‐quality group III nitride materials.