Surface kinetics in AlN growth: A universal model for the control of surface morphology in III-nitrides

AlN epitaxial thin films were grown on both vicinal (0001)-oriented native single crystal AlN substrates and AlN templates grown on vicinal (0001) -oriented sapphire to develop a surface kinetic framework for the control of surface morphology. A Burton, Cabrera, and Frank (BCF) theory-based model is formulated and utilized to understand the dependence of the surface kinetics on the vapor supersaturation, sigma, and substrate misorientation angle, alpha. The surface energy of the Al-polar surface of AlN was experimentally determined using BCF theory to be 149 +/- 8 meV/angstrom(2). The critical misorientation angle for the onset of step-bunching was determined to be similar to 0.25 degrees for a growth rate of 500 nm/h and temperature of 1250 degrees C. Transitioning from a surface with 2D nuclei to one with bilayer steps required a decrease in sigma or an increase in alpha, whereas the suppression of step-bunching required an increase in sigma or a decrease in alpha. (C) 2016 Elsevier B.V. All rights reserved.