Growth and Characterization of Crack-Free Semi-Polar (1-101) GaN on 7°-off (001) Si Substrates by Metal-Organic Chemical Vapor Deposition

This paper reports a selective growth method for growing crack-free semi-polar (1-101) GaN on V-grooved 7°-off (001) Si substrates by using a reticular SiO2 mask. This method effectively reduces the effect of thermal stress on GaN so that crack-free (1-101) GaN films as thick as 1 μm are obtained after coalescence of the selectively grown hexagonal pyramids. Transmission electron microscopy investigations clearly show the presence of low dislocation density regions, which result from the bending of dislocations toward the {1-100} directions during the facet growth stage. The stress and corresponding localized surface defects in GaN grown on the patterned Si substrates are depicted by cathodoluminescence spectroscopy.