A method was described for reducing threading dislocation densities in (00•1)-oriented GaN from 5.0 x 109 to 3.1 x 107/cm2 (for coalesced films) or to below 5 x 106/cm2 (for partially coalesced films) in a single step, without lithography. Lattice-matched dislocation-blocking scandium nitride interlayers were deposited onto a 500nm GaN-on-sapphire template. Dislocation-free GaN islands grown on the ScN interlayer nucleated both on the interlayer and on tiny areas of the GaN template exposed through openings in the interlayer. However, some dislocations were generated above the interlayer during subsequent island coalescence.

Dislocation Reduction in Gallium Nitride Films Using Scandium Nitride Interlayers. M.A.Moram, Y.Zhang, M.J.Kappers, Z.H.Barber, C.J.Humphreys: Applied Physics Letters, 2007, 91[15], 152101