Fabrication of a low threading dislocation density ELO-AlN template for application to deep-UV LEDs

Abstract

We have fabricated low threading dislocation density (TDD) AlN templates on sapphire substrates for application to deep-ultraviolet (DUV) light-emitting diodes (LEDs) by employing an epitaxial lateral overgrowth (ELO) process. An AlN stripe structure with a width of 5 μm and a spacing of 3 μm was formed by using inductive coupled plasma (ICP) etching. The AlN stripes were completely coalesced and embedded to create a flat surface after the growth of an approximately 15 μm-thick ELO-AlN layer, grown by low-pressure metal-organic chemical vapor deposition (LP-MOCVD). We systematically investigated the appropriate V/III ratio and growth temperature for the ELO-AlN. The edge-type TDD of the AlN was reduced from 2×109 cm-2 (AlN stripe region) to 3×108 cm-2 (in the wing region of the ELO-AlN), as estimated by cross-sectional transmission electron microscope (TEM) imaging. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.