Semipolar GaN Films on Prism Stripe Patterned a-Plane Sapphire Substrates

Abstract

A (10 (1) over bar4) semipolar GaN layer was grown on periodic stripe patterned a-plane sapphire substrate fabricated by using two-steps etching process. The stripes in prism shape were inclined with sapphire c-axis in 60 degrees. The orientation relationship between semipolar GaN and sapphire is (0002)(GaN)//(2 (1) over bar(1) over bar(3) over bar)(sapphire) and [2 (1) over bar(1) over bar0](GaN)//[23 (5) over bar2](sapphire) as defined by selected area diffraction in transmission electron microscopy (TEM). Growth of semipolar GaN on the sidewalls of the prism stripes is evidenced from TEM and X-ray phi scan. The quality of semipolar GaN film is reasonably good as examined with X-ray rocking curves. In addition, TEM and cathodoluminescence results show that the dislocation density in the semipolar GaN is significantly reduced near the film surface. (C) 2012 The Electrochemical Society. All rights reserved.