Electrophysical parameter comparison of 2DEG in AlGaN/GaN heterostructures grown by the NH3-MBE technique on sapphire and silicon substrates

Abstract

A comparative study of the structural properties of GaN layers and the electrophysical parameters of 2DEG in AlGaN/GaN heterostructures grown by ammonia molecular beam epitaxy on sapphire and silicon substrates using identical buffer layer designs has been carried out. It is demonstrated that GaN layers grown under the same growth conditions have the similar surface morphology, regardless of the substrate material. It is shown that the dislocation density of compressed GaN layers grown on sapphire substrates up to 5 times lower than in crack-free and stretched GaN layers grown on silicon substrates. The measured values of electron mobility in heterostructures with 2DEG grown on sapphire substrates are higher by 30% than on silicon substrates (∼1600 cm2/V × s and ∼1200 cm2/V × s).