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

Abstract

We report on the plasma-assisted molecular-beam epitaxial growth of (112¯2)-oriented GaN/AlN nanostructures on (11¯00) m-plane sapphire. Moderate N-rich conditions enable to synthesize AlN(112¯2) directly on m-sapphire, with in-plane epitaxial relationships [112¯3¯]AlN∥[0001]sapphire and [11¯00]AlN∥[112¯0]sapphire. In the case of GaN, a Ga-excess of one monolayer is necessary to achieve two-dimensional growth of GaN(112¯2). Applying these growth conditions, we demonstrate the synthesis of (112¯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.