Analysis Of The Relation Between Leakage Current And Dislocations In Gan-Based Light-Emitting Devices

In order to understand the origin of leakage current, light emitting devices were grown on two different templates with apparently different dislocation density: one on thin GaN template (similar to 2 mu m) with higher dislocation density (low x 10(9) cm(-2)) prepared by metal-organic vapor-phase epitaxy (sample A), and the other on thick GaN template (20 mu m) with comparatively low dislocation density (high x 108 CM 2) by hydride vapor-phase epitaxy (sample B). Especially, the template B showed very low value of the dislocation density for a screw component, 2.2 x 10(7) cm(2) evaluated by transmission electron microscope and 2.3 x 10(7) cm(-2) approximated by the Williamson-Hall plot which was evaluated by high resolution X-ray diffraction, respectively. On the other hand, sample A showed one order higher, low x 10(8) cm(2), than that of sample B for a screw component. Sample A showed the larger leakage current (more than two orders of magnitude) than sample B in a forward-biased region and a reverse-biased region also. It is expected that the screw dislocation were strongly contributed to the leakage current of forward and reverse I-V regions in LEDs. (c) 2007 WILEY-VCH Vertag GmbH & Co. KGaA, Weinheim.