Surface diffusion during metalorganic vapor phase epitaxy of AlN

Abstract

AbstractThe surface diffusion of Al adatoms during metalorganic vapor phase epitaxy of AlN was investigated, using sapphire substrates with different mis‐orientations. It was found that the diffusion length during modified migration‐enhanced epitaxy (MEE) is about 40 nm and comparable to that of conventional MEE under the current growth conditions. The enhancement of the diffusion length by alternating supply of source precursors was also demonstrated. The screw dislocation density in the modified‐MEE‐grown AlN was extracted to be as low as 2.2 × 106 /cm2 from X‐ray diffraction, while the chemical etching by KOH solution revealed an etch pit density of 1.0 × 106 /cm2, both of which indicated its superior structural properties. The chemical etching also evidenced that the grown AlN has Al polarity. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)