Different buffer approaches for AlGaN/GaN heterostructures epitaxy on Si(111) substrates

A 2 μm crack-free AlGaN/AlN/GaN heterostructure stack was successfully grown on 2-inch Si(111) substrates by metal organic chemical vapor deposition with high temperature AlN nucleation layer and low temperature AlN interlayer. This approach of GaN buffer deposition on silicon substrate was compared with another ones, utilizing graded AlGaN and super lattice AlN/GaN buffers. The electron mobility of two-dimensional electron gas of AlGaN/AlN/GaN/Si(111) heterostructure measured by impedance spectroscopy was 2080 m²V^-1s^-1 compared to 2415 m²V^-1S^-1 obtained for reference AlGaN/AlN/GaN/sapphire heterostructure.