Defect blocking via laterally induced growth of semipolar (1 0(1)over-bar 1) GaN on patterned substrates

Semipolar (10 (1) over bar1) GaN thin films with state-of-the-art optical and structural quality have been obtained on silicon substrates by metal organic chemical vapor deposition using a novel defect reduction method. We initially apply a classical patterning approach on Si (001) 7 degrees off substrates to reveal the Si (111) facets over which the subsequent inclined epitaxy will be carried out. After the growth of AlN, the sample is etched with SF6 before the GaN growth is done on the same structure. The process has shown to induce the spontaneous formation of a defect blocking layer that substantially reduces the presence of threading dislocations and basal stacking faults. This is confirmed by correlated optical and structural characterizations. Further, a simple model explaining the origin and working-principle of the blocking layer will be discussed.