Analysis of the relation between leakage current and dislocations in GaN‐based light‐emitting devices

Abstract

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 (∼2 µm) with higher dislocation density (low × 10 9 cm -2 ) prepared by metal-organic vapor-phase epitaxy (sample A), and the other on thick GaN template (∼20 µm) with comparatively low dislocation density (high × 10 8 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 × 10 7 cm -2 evaluated by transmission electron microscope and 2.3 × 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 × 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.

Spectroscopy of defects in neutron irradiated ammono-thermal GaN by combining photoionization, photoluminescence and positron annihilation techniques

“…3(a)) spectra. A clear decrease of the intensity of the YG-PL band with the enhancement of fluence is clearly observed only for large fluences >10 16 n/cm 2 . The intensity of B-PL decreases nearly monotonically with the increase of irradiation fluence.…”

“…This determines the dislocation density not less than 10 9 cm -2 [15]. Especially, screw dislocations strongly affect the electrical properties of the electronic devices [16]. There exists the epitaxial-lateral-overgrowth (ELO) technology, which allows making of GaN layers relatively clean from dislocations.…”