High-quality AlN/AlGaN templates were prepared by using a trimethylaluminum

pulsed-supply growth method. A dramatic improvement in the surface roughness

of the AlN/AlGaN layers was achieved by introducing a short-period pulsed supply of trimethylaluminum during the growth intervals of a standard AlGaN growth

regime. It was suggested that the improvement in surface roughness was due to the

realization of stable group-III (+c) polarity via the growth of an Al-rich surface. In

addition, it was found that this method was effective for reducing threading

dislocation densities. The threading dislocation density was reduced from 2.9 x 109

to 1.1 x 109/cm2 by introducing the trimethylaluminum pulsed supply growth.

Improvement of Surface Roughness and Reduction of Threading Dislocation

Density in AlN/AlGaN Templates on Sapphire by Employing Trimethylaluminum

Pulsed Supply Growth. N.Noguchi, T.Ohashi, N.Kamata, H.Hirayama: Physica

Status Solidi C, 2008, 5[6], 1968-70