Characterisation of Defects at Non-Polar GaN/InGaN Junctions in Novel Materials for Application in Light Emitting Diodes
Journal of Physics, Conference Series
A dissociation mechanism for the [a+c] dislocation in GaN P D Nellist, P B Hirsch, S Rhode et al. -Topical Review: Development of overgrown semi-polar GaN for high efficiency green/yellow emission T Wang -Optoelectronic device physics and technology of nitride semiconductors from the UV to the terahertz Theodore D Moustakas and Roberto Paiella -This content was downloaded from IP address 220.127.116.11 on 27/07 Abstract. Despite the significant progress in the area, III-nitride LEDs still
... de LEDs still suffer from reduced efficiency due to a high dislocation density associated with a lack of suitable growth substrates and strong polarisation fields along the c-axis, the predominant growth direction, resulting in the quantum confined stark effect (QCSE). The novel materials studied here have been developed with the aim of reducing both of these effects and consist of a series of GaN and InGaN layers deposited by chemical vapour deposition on the non-polar, m-plane facets of core structures prepared from c-axis GaN thin films. A dual-beam FIB has been used to prepare a and c-plane sections through these novel structures in order to characterise the defects in the core and non-polar junction using, both diffraction contrast and high resolution, TEM and STEM. The dislocations in the c-axis GaN were generally observed to be confined to this region but the non-polar layers had a high density of defects. The latter include unusual flag type defects which are shown to be comprised of pyramidal dislocations and basal-plane stacking faults, with the Burgers vectors determined via g·b analysis.