Influence of substrate polarity of (0 0 0 1) and (0 0 0 1¯)GaN surfaces on hydride vapor-phase epitaxy of InN

InN layers were grown on both-sides-polished (0 0 0 1) freestanding GaN substrates by hydride vapor-phase epitaxy (HVPE) in the growth temperature range from 450 to 650 °C with an input partial pressure of NH3 ranging from 3.0×10−2 to 3.8×10−1 atm. An In-polar InN layer was grown on the (0 0 0 1) Ga-polar surface, while a N-polar InN layer was grown on the (0 0 0 1¯) N-polar surface of the freestanding GaN substrate. The InN layers of both polarities grown at 550 °C had smooth surfaces, ideal lattice constants of the wurtzite InN structure, and a minimum optical absorption edge energy of about 0.75 eV. Surface morphologies of the InN layers were also dependent on the NH3 input partial pressure. The surface of In-polar InN became smoother under a high NH3 input partial pressure, whereas the N-polar InN required a low NH3 input partial pressure to achieve a smooth surface.