Embedded AlN/GaN multi-layer for enhanced crystal quality and surface morphology of semi-polar (11-22) GaN on m-plane sapphire
Document Type
Article
Publication Date
1-1-2018
Abstract
We demonstrate high quality semi-polar (11-22) gallium nitride thin film grown on m-plane sapphire substrate with the insertion of AlN/GaN multi-layer via MOCVD. The influence of three different number of multi-layers AlN/GaN pairs on the crystal quality and surface morphology of semi-polar (11-22) gallium nitride thin film is investigated. The surface morphology analysis strongly suggests that increasing the number of AlN/GaN pairs from 20 to 60 suppresses the arrowhead-like and undulated features. The increase of AlN/GaN pairs also enhanced the surface quality, with the root mean square roughness improving from 16.24 nm to 6.08 nm. The abruptness of the interface between the AlN/GaN pairs was seen to improve significantly upon reaching the 40th pair where a continuous thin layer was clearly observed for each pair. The crystal quality was also observed to be enhanced at higher number of AlN/GaN pairs, where the on- and off-axis X-ray rocking curve showed significant reduction in the full width at half maximum of at least ~10% and 20%. Finally, x-ray reciprocal space mapping analysis further confirms the enhancement of the crystal quality as the diffuse scattering streak was suppressed, which may indicate a significant reduction of the defect density.
Keywords
Gallium nitride, Multi-layer, Semi-polar, Surface morphology, Thin film
Divisions
PHYSICS
Funders
University Malaya for UMRG : RP039B-18AFR , RP039A-18AFR & RG368-15AFR and FRGS : FP046-2015A,CREST Gallium Nitride on Gallium Nitride Collaboration (PVD15-2015),Ministry of Higher Education (MOHE) for the Long-Term Research Grant ( LRGS ) account/project No: LR001A-2016A for project funding
Publication Title
Materials Science in Semiconductor Processing
Volume
86
Publisher
Elsevier