Influence of Si doping on size of GaN quantum dots grown by molecular beam epitaxy under Ga‐rich conditions

Abstract

AbstractThe size control of Si‐doped GaN/AlN quantum dots (QDs) was studied by using molecular beam epitaxy under Ga‐rich conditions that were widely used for high‐quality thin‐film growth. The formation of GaN QDs was affected by Si‐doping in contrast with that of the QDs under N‐rich condition. Atomic force microscopy images of Si‐doped GaN QDs and undoped GaN QDs were clearly different. Diameters of Si‐doped GaN QDs decreased with increase in Si concentration within 1 x 1017‐1020 cm–3, whereas heights were almost constant. Micro‐Raman spectroscopy showed that the LO phonon frequency shifted toward lower wavenumbers with increase in Si concentration. These results suggest that Si doping may affect the length of Ga‐N bonds related with the elastic strain and, as a result, influence the aspect ratio of QDs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)