Abstract
AlN layers were grown on a c-plane sapphire substrate by metal–organic vapor phase epitaxy (MOVPE) at 1350 °C. The structural quality of the grown AlN layers was drastically improved by post-growth annealing in mixed hydrogen, ammonia, and trimethylgallium ambiance at 1350 °C. As a first step, we grew the AlN layers exhibiting a double-domain structure with an in-plane rotation angle of ∼4°. Then, the domain structure was changed from double to single by the post-growth annealing. After 20 min post-growth annealing, the surface possessed an atomically flat step-and-terrace structure with a root-mean-square value of ∼0.11 nm measured across 5 × 5 µm2. The full-width at half maximum values for 0002 and 101̄4 AlN reflections using x-ray diffraction were as small as ∼75 and ∼280 arcsec, respectively. Since this work provides a simple continuous MOVPE growth procedure to improve the structural quality of AlN/sapphire, it is advantageous to the industrial fabrication of AlxGa1−xN-based ultraviolet light-emitters.
Highlights
We investigated the influence of trimethylgallium (TMGa) flow during post-growth annealing in mixed H2 and NH3 ambiance on the structural quality of AlN/sapphire
A simple metal–organic vapor phase epitaxy (MOVPE) growth procedure was developed to improve the structural quality of AlN/sapphire
For Sample a, post-growth annealing was performed in mixed H2 and NH3 ambiance
Summary
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