Homoepitaxial growth of AlN on a 2-in.-diameter AlN single crystal substrate by hydride vapor phase epitaxy

Abstract

Homoepitaxial growth of a thick AlN layer on a 2-in.-diameter single crystal AlN(0 0 0 1) substrate prepared by physical vapor transport (PVT) was investigated by hydride vapor phase epitaxy (HVPE). A water-clear crack-free homoepitaxial layer with a thickness of 500 μm or more could be grown on the entire surface of the PVT-AlN substrate. No degradation of crystallinity was observed during homoepitaxial growth. X-ray rocking curve measurements of the homoepitaxial layer showed small full widths at half maximum of 11–16 arcsec, the same as those for the PVT substrates. A freestanding AlN substrate prepared from the homoepitaxial layer showed high optical transmittance in the deep ultraviolet region owing to low impurity concentrations.