Effect of substrate orientation on photoluminescence of GaNAs

The effect of substrate orientation on photolumincscence (PL) properties ha s been explored for GaNAs grown by metalorganic vapor phase cpitaxy using d imethylhydrazine as a nitrogen precursor. The PL spectra show improvements in the emission intensity and linewidth, and a decrease in a deep level emi ssion, with the surface tilled from (100) to (411)A towards (111)A. For the peak position dependence on excitation intensity, a blueshift revealed by the increased excitation intensity is also depressed with higher-index subs trates. These improvements could be obtained as a consequence of reductions in deep level defects, residual impurity incorporations, and spatial fluct uations in nitrogen concentration, with an increase in the A-type step dens ity. In addition to the improved optical quality, (411)A shows a relatively large redshift in bandgap. Our results indicate that the use of high-index substrates is effective in GaNAs applications.