<title>Pyramid nano-voids in GaN and InGaN</title>

Abstract

High resolution transmission electron microscopy and aberration-corrected scanning transmission electron microscopy (STEM) reveal a new void defect in GaN, Si-doped GaN, and InGaN. The voids are pyramid shaped with symmetric hexagonal {0001} base facets and {10-11} side facets. The pyramid void has a closed or open core dislocation at the peak of the pyramid, which continues up along the [0001] growth direction. The closed dislocations have a 1/3 11-20 edge dislocation Burgers vector component, consistent with known threading dislocations. The open core dislocations are hexagonal shaped with pure screw character, {10-10} side facets, varying lateral widths, and varying degrees of hexagonal symmetry. STEM electron energy loss spectroscopy spectrum imaging revealed a larger C concentration inside the void and below the void than above the void. We propose that carbon deposition during metal organic chemical vapor deposition growth acts as a mask, stopping the GaN deposition locally. Subsequent layers of GaN deposited around the C covered region create the overhanging {10-11} facets, and the meeting of the six {10-11} facets at the pyramid's peak is not perfect, resulting in a dislocation.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.