Effect of an AlN buffer layer on the epitaxial growth of InN by molecular-beam epitaxy

The effect of an AlN buffer layer on the epitaxial growth of InN by molecular-beam epitaxy (MBE) is studied. Using an AlN buffer layer can significantly improve the structural and electrical properties of InN. With increasing thickness of the AlN buffer layer, the Hall mobility of InN will monotonically increase while the electron carrier concentration decreases. The surface morphology of the film also improves. A Hall mobility of more than 800 cm2/V s with a carrier concentration of 2–3×1018 cm−3 at room temperature can be routinely obtained on ∼0.1 μm InN film. More importantly, it is found that under optimum growth conditions, by using an AlN buffer layer, InN films with comparable quality can be achieved by the conventional MBE technique compared to InN grown by migration-enhanced epitaxy. Increasing InN thickness also increases Hall mobility.