MOCVD growth of N-polar GaN on on-axis sapphire substrate: impact of AlN nucleation layer on GaN surface hillock density

Abstract

We report on the impact of growth conditions on surface hillock density of N-polar GaN grown on nominally on-axis (0001) sapphire substrate by metal organic chemical vapor deposition (MOCVD). Large reduction in hillock density was achieved by implementation of an optimized high temperature AlN nucleation layer and use of indium surfactant in GaN overgrowth. A reduction by more than a factor of five in hillock density from 1000 to 170 hillocks/cm${}^{-2}$ was achieved as a result. Crystal quality and surface morphology of the resultant GaN films were characterized by high resolution x-ray diffraction and atomic force microscopy and found to be relatively unaffected by the buffer conditions. It is also shown that the density of smaller surface features is unaffected by AlN buffer conditions.

arXiv comment17 pages, 4 figures, 2 tables

References in corpus (2)

• Adatom Diffusion at GaN (0001) and (000bar1) Surfaces
• Polarization-Engineering in III-V Nitride Heterostructures: New Opportunities For Device Design

Cited by in corpus (3)

• Dopant-defect interactions and their impact on local crystal stoichiometry studies in Mg-doped GaN via atom probe tomography
• Photoemission characterization of N-polar III-Nitride photocathodes as bright electron beam source for accelerator applications
• Polar charge induced self-assembly: An electric effect that causes non-isotropic nanorod growth in wurtzite semiconductors