Effect of MOVPE growth conditions on AlN films on annealed sputtered AlN templates with nano-striped patterns

Abstract

The metalorganic vapor phase epitaxial (MOVPE) growth of AlN films was performed on face-to-face annealed sputtered AlN templates (FFA Sp-AlN) having a nano-striped pattern with a period of 300 nm and depth of 120 nm. Then, the effect of MOVPE growth conditions on the crystallinity was elucidated. The faceted structure clearly changed with the growth temperature (Tg), following the same trend as the epitaxial lateral overgrowth of GaN film on micro-patterned GaN. High Tg levels enhanced the lateral growth, and thus with a high Tg of 1300 °C, the coalescence in the early growth stage resulted in AlN films with coalesced surfaces and a thickness of 1 µm. For the AlN film grown at a Tg of 1300 °C, the threading dislocation density (TDD) was estimated to be 6.0 × 108 cm−2. This value proved that coalesced AlN films on nano-patterned FFA Sp-AlN templates with low TDDs could be achieved with the appropriate MOVPE growth conditions. The compressive strain in the AlN film on nano-patterned FFA Sp-AlN was lower than that of the film grown on FFA Sp-AlN without a pattern.