Growth of c-Plane GaN Films on (100) γ-LiAlO₂ by Hydride Vapour Phase Epitaxy

Summary

Structural analysis of c-plane GaN nucleation layers on (100) γLiAlO₂ and freestanding 2 inch c-plane GaN wafers is presented. The nucleation layers contain a number of hexagonal pits. The pit formation in nucleation layers might be an origin for the formation of macroscopic pyramids, which are coupled on V-pits in the freestanding 2 inch GaN layers. The pyramids start growing at the interface to LiAlO₂. They consist of wurtzite GaN, which is brown in colour. The brown GaN regions show an extremely high defect density. The freestanding HVPE-grown GaN layers have Ga polarity.