Low threading dislocation density AlN templates were fabricated on sapphire substrates for application in deep-ultraviolet light-emitting diodes by employing an epitaxial lateral overgrowth process. An AlN stripe structure with a width of 5μm and a spacing of 3μm was formed by using inductive coupled plasma etching. The AlN stripes were completely coalesced and embedded to create a flat surface after the growth of an approximately 15μm-thick epitaxial lateral overgrowth AlN layer, grown by low-pressure metal-organic chemical vapour deposition (LP-MOCVD). A systematic investigation was made of the appropriate V/III ratio and growth temperature for the epitaxial lateral overgrowth AlN. The edge-type threading dislocation density of the AlN was reduced from 2 x 109/cm2 (AlN stripe region) to 3 x 108/cm2 (in the wing region of the epitaxial lateral overgrowth-AlN), as estimated by cross-sectional transmission electron microscope imaging.

Fabrication of a Low Threading Dislocation Density ELO-AlN Template for Application to Deep-UV LEDs. H.Hirayama, S.Fujikawa, J.Norimatsu, T.Takano, K.Tsubaki, N.Kamata: Physica Status Solidi C, 2009, 6[S2], S356-9