Native oxides and regrowth on III–N surfaces

The characteristics of native oxides on epitaxially grown III–N materials, particularly GaN and AlN, were studied using reflection high-energy electron diffraction (RHEED) and photoluminescence (PL) spectroscopy. RHEED observations show no sign of the formation of native oxides on III–N surfaces by air exposure, contrary to the III–As surfaces which readily oxidize upon exposure to air. One result of this behavior is that high-quality regrowth is possible on air-exposed III–N surfaces. Two GaN samples were grown on top of AlN buffer layers using molecular beam epitaxy, one sample was grown continuously while the other had an air-exposed interface in the AlN buffer. PL studies show that the luminescence properties of GaN layers in both samples are comparable and that material quality is not degraded due to the air exposure of the AlN buffer.