Epitaxial growth of hexagonal pillar structure InN single crystals on sapphire (11−20) substrate by halide CVD method under atmospheric pressure

Abstract

InN, one of III–V group compounds, has attracted attention owing to its optical properties in the infrared region. A high quality crystal growth for InN, however, is a key issue because InN is unstable at high temperature due to its thermal instability. Moreover, a microstructure control of InN by controlling a growth condition is desired for various optical applications. Atmospheric pressure halide chemical vapor deposition (APHCVD) method enables a single-crystal growth of InN at moderate growth temperature. In the present study, influence of the growth temperature and time on microstructure of hexagonal-pillar-structure InN single crystals by the APHCVD method on sapphire (1120) substrate is investigated using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The growing temperature of the InN influences significantly to the microstructure of the InN crystal; flower like structures at low temperature of 560 °C, pillar structures at moderate temperature of 590 to 610 °C, and coalesced pillar structure at 640 °C.