4 inch 11 μm high-quality AlN thick films grown on nanopatterned sapphire substrates

A high-quality AlN thick film with 11 mu m thickness and low defect density was grown on a 4 inch hexagonal hole nano-patterned sapphire substrate by metal oxide chemical vapor deposition. The density of dislocation etch pits in the AlN heteroepitaxial film reached 1.1 x 107 cm-2. The surface and microstrcutres of the AlN thick film were characterized in detail. The dislocation evolution mechanism and stress evolution of AlN were investigated. Dislocations were mainly generated at the interface between the sapphire and AlN, and the voids above the patterned region were generated by the undesirable grain boundaries caused by the lateral epitaxy of AlN and the substrate during the growth process, which prompted a large number of screw dislocations to bend and merge, and while some mixed dislocations to merge and extend upwards, resulting in a high-quality AlN thick film.