Quality-enhanced AlN epitaxial films grown on Al substrates by two-step growth

Abstract

Quality-enhanced AlN epitaxial films have been grown on Al substrates by pulsed laser deposition with two-step growth by the combination of low-temperature (LT) and high-temperature (HT) growth. The effect of the HT growth temperature on the interfacial property, surface morphology and crystalline quality of the as-grown AlN epitaxial films is studied in detail. It is found that as the HT growth temperature increases from 450 to 650 °C, the AlN/Al hetero-interfaces of ∼300 nm thick AlN epitaxial films remain sharp and clear, and the surface morphology and crystalline quality of ∼300 nm thick AlN epitaxial films are improved gradually. Especially, the ∼300 nm thick AlN epitaxial films grown at a HT growth temperature of 650 °C show sharp and abrupt AlN/Al hetero-interfaces, very smooth surfaces with a root-mean-square surface roughness of 1.1 nm, and high crystalline quality with full-widths at half-maximum for AlN(0002) and AlN(102) X-ray rocking curves of 0.45° and 0.72°, respectively. The quality-enhanced AlN epitaxial films on Al substrates are of paramount importance for the fabrication of highly-efficient AlN-based devices.