Journal
JOURNAL OF PHYSICS D-APPLIED PHYSICS
Volume 47, Issue 13, Pages -Publisher
IOP PUBLISHING LTD
DOI: 10.1088/0022-3727/47/13/135107
Keywords
trench defect; cathodoluminescence; InGaN; multiple quantum wells; scanning electron microscopy
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Funding
- UK EPSRC [EP/I012591/1, EP/H004157/1, EP/IO29141/1]
- University of Strathclyde
- EPSRC [EP/I029141/1, EP/H004157/1, EP/H019324/1, EP/I012591/1] Funding Source: UKRI
- Engineering and Physical Sciences Research Council [EP/I029141/1, EP/I012591/1, EP/H019324/1, EP/H004157/1] Funding Source: researchfish
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Optoelectronic devices based on the III-nitride system exhibit remarkably good optical efficiencies despite suffering from a large density of defects. In this work we use cathodoluminescence (CL) hyperspectral imaging to study InGaN/ GaN multiple quantum well (MQW) structures. Different types of trench defects with varying trench width, namely wide or narrow trenches forming closed loops and open loops, are investigated in the same hyperspectral CL measurement. A strong redshift (approximate to 90 meV) and intensity increase of the MQW emission is demonstrated for regions enclosed by wide trenches, whereas those within narrower trenches only exhibit a small redshift (approximate to 10 meV) and a slight reduction of intensity compared with the defect-free surrounding area. Transmission electron microscopy (TEM) showed that some trench defects consist of a raised central area, which is caused by an increase of about 40% in the thickness of the InGaN wells. The causes of the changes in luminescences are also discussed in relation to TEM results identifying the underlying structure of the defect. Understanding these defects and their emission characteristics is important for further enhancement and development of light-emitting diodes.
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