GaAs epitaxial growth on R-plane sapphire substrate

Abstract

Achieving epitaxial growth of III-As on r-plane sapphire would potentially allow the integration of both laser and amplifier with corresponding RF electronics. Here we report on the growth of high-quality GaAs on an r-plane sapphire substrate by molecular beam epitaxy. The epitaxial relationship between GaAs and r-plane sapphire is observed and explained. GaAs on r-plane sapphire resulted in (111) orientation, similar to growth orientation observed on c-plane sapphire. However, in comparison with growth of GaAs growth on a c-plane sapphire substrate, a stronger interaction is observed between GaAs on r-plane sapphire. The effect of growth temperature is also investigated for GaAs growth on r-plane sapphire. It is found that GaAs island size, density, and orientation can be tuned by varying the growth temperature. Finally, a thin AlAs nucleation layer on r-plane sapphire has been introduced to study its effect on the growth of GaAs. The introduction of the AlAs nucleation layer is found to enhance the wetting of GaAs but at the expense of introducing twinning defects.