Stranski-Krastanow growth of (11(2)over-bar2)-oriented GaN/AlN quantum dots

Semipolar GaN (11 (2) over bar2) deposited on AlN(11 (2) over bar2) by plasma-assisted molecular-beam epitaxy can follow the Frank-Van der Merwe or the Stranski-Krastanow growth mode as a function of the Ga/N ratio. N-rich grown GaN relaxes elastically at a critical thickness but the resulting GaN islands present multiple crystallographic orientations. In contrast, after deposition of a few two-dimensional GaN monolayers under Ga-rich conditions, a growth interruption in vacuum induces (11 (2) over bar2)-oriented islanding. Applying this latter procedure, we have synthesized GaN/AlN quantum dot superlattices with reduced internal electric field. (C) 2009 American Institute of Physics. [DOI:10.1063/1.3095499]