Proposal and achievement of a relatively Al-rich interlayer for In-rich Al x In1−x N films deposition

Abstract

Ternary In-rich AlxIn1−xN films were successfully grown on Si (111) and (0001) sapphire substrates by radio-frequency magnetron sputtering on a relatively Al-rich AlxIn1−xN layer after AlN buffer. X-ray diffraction (XRD) patterns of the films indicate highly c axis-oriented wurtzite structure and the indium content of about 0.76 has been evaluated according to the Vegard’s law. An Al-rich AlxIn1−xN transition layer was formed between the ultimate In-rich AlxIn1−xN film and the AlN buffer, which served as a further buffer to alleviate mismatch. X-ray photoelectron spectroscopy (XPS) depth profiling analyses confirm the alternative of indium and aluminum composition and the unavoidable oxygen impurities from surface to bulk. Owing to high indium content, obvious E2H and InN-like A1 (LO) phonon model accompanying with slight AlN-like A1 (LO) phonon model are observed. Hall effect measurements demonstrate n-type electrical conductivity in these alloys with carrier concentrations n=1019 cm−3. The strain in In-rich AlxIn1−xN films can be significantly reduced by introducing an Al-rich interlayer, facilitating the improvement of film quality for diverse device applications.