Initial boron growth on GaN and AlN surfaces by molecular beam epitaxy

Abstract

Elemental boron was thermally deposited, using the MBEtechnique, on surfaces of AlN and GaN. To suppress boron clustering, nitrogen was supplied from an RF nitrogen plasma source. Reflection high energy electron diffraction was used to monitor the surface before and during the growth. On the GaN surface, low concentrations of boron (̃0.1 ML) resulted in additional 6-fold highly streaky reflection rods indicating a reconstructed GaN(0001) surface. By increasing the boron concentration to ̃0.5 ML, however, the growth resulted in the formation of 3D islands as observed by spots in the RHEED pattern. Islands were also observed by atomic force microscopy and scanning electron microscopy. The AlN surface produced surface morphological features already for the lowest boron concentration, i.e. ̃0.1 ML coverage. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA