Effects of miscut of prestructured sapphire substrates and MOVPE growth conditions on (112¯2) oriented GaN

• We adjusted the orientation of the (112¯2) GaN plane towards the wafer surface.
• The c-plane of GaN is tilted by more than 1° towards the c-plane of the sapphire template.
• High growth temperature above 1066 °C and moderate V/III ratio of 150 seems to be beneficial.

In this work, the influence of sapphire mis-orientation on the quality of coalesced (112¯2) GaN layers grown on r-plane prestructured sapphire substrates (r  -PSS) is investigated. It was found that the angle of the GaN (112¯2) plane towards the surface plane of the sapphire wafer can be adjusted by the mis-orientation of the substrate. Furthermore, we discovered that the c-direction of GaN is tilted by more than 1° towards the c-direction of the sapphire wafer.In a second experiment, the influence of the MOVPE growth temperature, V/III ratio and reactor pressure on the coalesced layer has been studied. While a high temperature and small V/III ratio are beneficial, the reactor pressure did not show any significant impact on the crystal quality and surface roughness.