Epitaxial lateral overgrowth was used to reduce threading dislocation densities in

GaN. This paper reports transmission and scanning electron microscopy studies of

threading dislocations in GaN films grown by epitaxial lateral overgrowth onto

GaN nanocolumns produced either during growth by MBE (method 1), or by selforganised

patterning on a uniform layer grown by MOCVD (method 2). In method

1, isolated nanocolumns grew without threading dislocations, but some threading

dislocations formed when nanocolumns coalesced. Although some of these

threading dislocations extended through the overlayer, extensive lateral migration

of others, depending on the dislocation type, led to dislocation annihilation,

lowering the overall threading dislocation density. In method 2, a similar process of

lateral migration of threading dislocations was observed during epitaxial lateral

overgrowth, resulting in a continuous GaN overlayer with threading dislocation

densities less than 108/cm2.

The Reduction of Threading Dislocations in GaN Using a GaN Nanocolumn

Interlayer. L.Meshi, D.Cherns, I.Griffiths, S.Khongphetsak, A.Gott, C.Liu,

S.Denchitcharoen, P.Shields, W.Wang, R.Campion, S.Novikov, T.Foxon: Physica

Status Solidi C, 2008, 5[6], 1645-7