An assessment was made of 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 transmission electron microscopy 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 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 basal plane stacking fault density were reduced by all methods compared to the as-grown 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 basal plane stacking faults/cm. On the wafer scale, ScN interlayers were most effective: A single 5nm-thick ScN interlayer reduced the basal plane stacking fault 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