PAMBE growth of (1 1 2- 2)-oriented GaN/AlN nanostructures on m-sapphire

We report on the plasma-assisted molecular-beam epitaxial growth of ([email protected]?2)-oriented GaN/AlN nanostructures on ([email protected]?00) m-plane sapphire. Moderate N-rich conditions enable to synthesize AlN([email protected]?2) directly on m-sapphire, with in-plane epitaxial relationships [[email protected][email protected]?]"A"l"[email protected]?[0001]"s"a"p"p"h"i"r"e and [[email protected]?00]"A"l"[email protected]?[[email protected]?0]"s"a"p"p"h"i"r"e. In the case of GaN, a Ga-excess of one monolayer is necessary to achieve two-dimensional growth of GaN([email protected]?2). Applying these growth conditions, we demonstrate the synthesis of ([email protected]?2)-oriented GaN/AlN quantum well structures, showing a strong reduction of the internal electric field. By interrupting the growth under vacuum after the deposition of few monolayers of GaN under slightly Ga-rich conditions, we also demonstrate the feasibility of quantum dot structures with this orientation.