Dislocation reduction in gallium nitride films using scandium nitride interlayers
Moram, M A and Zhang, Y and Kappers, M J and Barber, Z H and Humphreys, C J
We describe a method of reducing threading dislocation densities in 0001-oriented GaN from (5.0±0.5)×10\^9cm\^−2 to (3.1±0.4)×10\^7cm\^−2 (for coalesced films) or to below 5×10\^6cm\^−2 (for partially coalesced films) in a single step, without lithography. Lattice-matched, dislocation-blocking scandium nitride interlayers are deposited on a 500nm GaN-on-sapphire template. Dislocation-free GaN islands grown on the ScN interlayer nucleate both on the interlayer and on tiny areas of the GaN template exposed through openings in the interlayer. However, some dislocations are generated above the interlayer during subsequent island coalescence.
Department of Materials
Imperial College London
Royal School of Mines
London, SW7 2AZ - UK