On the optical and microstrain analysis of graded InGaN/GaN MQWs based on plasma assisted molecular beam epitaxy

Pawan Mishra, Bilal Janjua, Tien Khee Ng, Dalaver H. Anjum, Rami T. Elafandy, Aditya Prabaswara, Chao Shen, Abdelmajid Salhi, Ahmed Y. Alyamani, Munir M. El-Desouki, Boon S. Ooi

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10 Scopus citations

Abstract

In this paper, c-plane stepped- and graded- InGaN/GaN multiple quantum wells (MQWs) are grown using plasma assisted molecular beam epitaxy (PAMBE) by in situ surface stoichiometry monitoring (i-SSM). Such a technique considerably reduces the strain build-up due to indium clustering within and across graded-MQWs; especially for QW closer to the top which results in mitigation of the quantum-confined Stark effect (QCSE). This is validated by a reduced power dependent photoluminescence blueshift of 10 meV in graded-MQWs as compared to a blueshift of 17 meV for stepped-MQWs. We further analyze microstrain within the MQWs, using Raman spectroscopy and geometrical phase analysis (GPA) on high-angle annular dark-field (HAADF)-scanning transmission electron microscope (STEM) images of stepped- and graded-MQWs, highlighting the reduction of ~1% strain in graded-MQWs over stepped-MQWs. Our analysis provides direct evidence of the advantage of graded-MQWs for the commercially viable c-plane light-emitting and laser diodes. © 2016 Optical Society of America.
Original languageEnglish (US)
Pages (from-to)2052
JournalOptical Materials Express
Volume6
Issue number6
DOIs
StatePublished - May 23 2016

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