Incorporation-related structural issues for beryllium doping during growth of GaN by rf-plasma molecular-beam epitaxy

Abstract
Beryllium incorporation was studied for both Ga-polarity and N-polarity GaN using a series of Be step-doped epitaxial layers. Dopant concentration profiles indicated that surface polarity-related incorporation differences are not pronounced for Be. Significant surface accumulation of Be occurs during growth with surface accumulations approaching a monolayer for heavier doping levels. Transmission electron microscopy studies indicate the surface layer of Be has a significant effect on the microstructure, particularly for near monolayer coverage.