Impact of sandwiched strain periodic multilayer AlN/GaN on strain and crystalline quality of a-plane GaN
Document Type
Article
Publication Date
5-6-2021
Abstract
We demonstrated high-quality single crystalline a-plane undoped-gallium nitride grown on a nonpatterned r-plane sapphire substrate via metal-organic chemical vapor deposition. The effect of four different numbers of sandwiched strain-periodic AlN/GaN multilayers on the strain state, crystal quality, optical and electrical properties was investigated. Field emission scanning electron microscopy and atomic force microscopy showed that the surface morphology was improved upon insertion of 120 pairs of AlN/GaN thin layers with a root-mean-square roughness of 2.15 nm. On-axis X-ray w-scan rocking curves showed enhanced crystalline quality: the full width at half maximum decreased from 1224 to 756 arcsec along the 0001] direction and from 2628 to 1360 arcsec along the 1-100] direction for a-GaN grown with 120 pairs of AlN/GaN compared to a-GaN without AlN/GaN pairs. Reciprocal space mapping showed that a-plane GaN with a high number of AlN/GaN pairs exhibits near-relaxation strain states. Room-temperature photoluminescence spectra showed that the sample with the highest number of AlN/GaN pairs exhibited the lowest-intensity yellow and blue luminescence bands, indicating a reduction in defects and dislocations. The a-plane InGaN/GaN LEDs with 120 pairs of SSPM-L AlN/GaN exhibited a significant increase (similar to 250%) in light output power compared to that of LEDs without SSPM-L AlN/GaN pairs.
Keywords
Light-emitting-diodes, Sapphire, Growth
Divisions
PHYSICS
Funders
Malaysia Ministry of Education (MOE) under Long-Term Research Grant (LRGS) [LR001-2016A (um.0000021/HME.LS)]
Publication Title
Scientific Reports
Volume
11
Issue
1
Publisher
Nature Research
Publisher Location
HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY