2-inch semi-polar (112) AlN templates prepared by high-temperature hydride vapor phase epitaxy

Abstract

Single-crystal semi-polar (112) AlN films are grown on 2-inch m-plane sapphire substrates by high-temperature hydride vapor phase epitaxy (HVPE). The introduction of the sapphire nitridation pretreatment and low-temperature AlN buffer layer suppresses the formation of undesired (103) and (101) AlN, leading to the desired single-crystal (112) AlN film. The high growth temperature promotes a shift in growth mode from three-dimensional islands to two-dimensional step flow. This facilitates grain coalescence, resulting in the formation of well-defined macro steps on the (112) AlN surface. The 9.02 μm-thick (112) AlN film exhibits excellent crystalline quality, as evidenced by the narrow full widths at half maximum of 547′′ and 634′′ for the X-ray rocking curves measured along the [113]_AlN and [100]_AlN directions, respectively. The surface of the 2-inch (112) AlN film is free of cracks and unmerged grains, providing a suitable substrate for the subsequent epitaxial growth of (112) AlN light emitter layers.