Fabrication of GaN/Alumina/GaN Structure to Reduce Dislocations in GaN

GaN/Alumina/GaN structures were fabricated to reduce dislocation density in GaN. Alumina films were deposited on GaN templates by electron cyclotron resonance plasma sputtering. GaN was regrown on the alumina films by metalorganic vapor phase epitaxy. It was found that GaN on alumina selectively regrown from pinholes in alumina by annealing prior to GaN regrowth. Hardly any of the dislocations in the GaN template propagated through the interlayer. Most of dislocations were terminated or bent at the interface between the alumina and regrown GaN. On the other hand, new vertical dark lines and horizontal dislocations were generated in regrown layer. The vertical lines were found to correspond to an inversion domain from convergent beam electron diffraction analysis.