A method was described for reducing threading dislocation densities, in 0001-oriented GaN, from 5.0 x 109/cm2 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 nucleate 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