The growth of gallium nitride layers with low dislocation density

The growth of «thick' (200 nm) AlN layers on sapphire at 1100−1150°C using STE3N MBE system is shown to be the key step to obtain high quality GaN-based heterostructures. An appropriate sequence of AlGaN transition layers grown on such an AlN both allows to reduce dislocation density in GaN down to (9−10)·108 cm-2 in comparison with GaN layers grown on «thin' (10 nm) low temperature AlN nucleation layer. Maximum electron mobility in 1.5 µm thick GaN silicon doped layer reaches 600−650 сm²/ (V·s) at electron concentrations (3−5)·1016 cm-3.