Study of Epitaxial Relationship in InN Growth on Sapphire (0001) by RF-MBE

InN films were grown directly on sapphire (0001) substrates by rf-MBE. In the direct growth of InN on sapphire substrates without nitridation process, InN films have the tendency to form a multi-domain structure due to in-plane rotation and they can have both the epitaxial relationship of [110]InN ∥ [110]sapphire and [100]InN ∥ [110]sapphire. The domain with [110]InN ∥ [110]sapphire is mainly observed at relatively low growth temperatures around 520 °C. The domain with [100]InN ∥ [110]sapphire, however, becomes dominant with increasing the growth temperatures to around 540 °C. The dominant factor in determining the main epitaxial relationship is found to be its growth temperature. However, this is highly sensitive to a small change in growth temperature which should be controlled within 20 °C.