This work assesses the relative effectiveness of different techniques to reduce

defect density in hetero-epitaxial, non-polar, a-plane GaN films grown on r -plane

sapphire by MOVPE. Plan view TEM was used to obtain the defect density of

films grown by different methods. The as-grown material was found to have a high

dislocation and basal plane stacking fault (BSF) density (1.9 x 1011/cm2 and 1.1 x

106/cm respectively). The four defect reduction techniques tested were: 3D-2D

growth, SiNx interlayers, ScN interlayers and epitaxial lateral overgrowth. Both

dislocation and BSF density were reduced by all methods compared to the asgrown

material. The lowest defect density was achieved in the (00•1) wing of the

epitaxial lateral overgrowth sample and was <106 dislocations/cm2 and 2.0 x 104

BSFs/cm. On the wafer scale, ScN interlayers were most effective: A single 5nmthick

ScN interlayer reduced the BSF density to 5.9 x 105/cm and the dislocation

density was reduced by two orders of magnitude to 1.8 x 109/cm2 compared to the

as-grown material.

Defect Reduction in Non-Polar (11¯20) GaN Grown on (1¯102) Sapphire.

C.F.Johnston, M.J.Kappers, M.A.Moram, J.L.Hollander, C.J.Humphreys: Physica

Status Solidi A, 2009, 206[6], 1190-3