Characterization of dislocations in GaN layer grown on 4-inch Si(111) with AlGaN/AlN strained layer superlattices

Dislocations in a GaN layer grown on 4-in. Si(111) with AlGaN/AlN strained layer superlattices using a horizontal metal-organic chemical vapor deposition system were characterized by transmission electron microscopy and scanning transmission electron microscopy. Pure screw dislocations were not found in the observed area but mixed and edge dislocations were found. The dislocation density in the GaN layer decreased from the bottom (similar to 2 x 10(10) cm(-2)) to the top (similar to 6 x 10(9) cm(-2)). Some dislocations were inclined from the c-axis, and half-loop dislocations were observed in the GaN layer. Plan-view weak-beam dark-field analysis indicated that the dislocation inclination was caused by climb and glide motions. (C) 2016 The Japan Society of Applied Physics