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Quantum Well Network Structures: Investigating Long-Range Thickness Fluctuations in Single InGaN/GaN Quantum Wells

Published online by Cambridge University Press:  01 February 2011

Nicole van der Laak ,
Rachel A Oliver ,
Menno J Kappers  and
Colin J Humphreys
Nicole van der Laak
Affiliation:
nkv21@cam.ac.uk, University of Cambridge, Materials Science and Metallurgy, Pembroke Street, Cambridge, N/A, CB2 3QZ, United Kingdom
Rachel A Oliver
Affiliation:
rao28@cam.ac.uk, University of Cambridge, Materials Science and Metallurgy, United Kingdom
Menno J Kappers
Affiliation:
mjk30@cam.ac.uk, University of Cambridge, Materials Science and Metallurgy, United Kingdom
Colin J Humphreys
Affiliation:
colin.humphreys@msm.cam.ac.uk, University of Cambridge, Materials Science and Metallurgy, United Kingdom
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Abstract

Gross well-width fluctuations have been observed in single green-emitting InGaN/GaN quantum wells (QWs) grown by two methods: (i) a “two-temperature” method, where the GaN barrier has been grown at a higher temperature than the InGaN layer, (ii) a single-temperature method, where the InGaN was annealed in a flow of NH3/N2, prior to capping. InGaN epilayers analogous to these QW structures have been grown and characterized by atomic force microscopy (AFM) and transmission electron microscopy (TEM). AFM reveals a network of interlinking InGaN strips. Compositional analysis across the InGaN strips has shown that the centres of these strips to be indium-rich compared to the strip-edges. Furthermore, we have correlated the position of threading dislocations (TDs) in relation to these InGaN strips and determined that 90 % of the TDs terminate at the channels between the InGaN strips or near the edges of the strips. We propose that confinement of charge carriers occurs in the indium-rich regions at the centre of the InGaN strips, preventing non-radiative recombination losses at dislocation sites.

Keywords

nitridetransmission electron microscopy (TEM)annealing
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 892 , 2005 , 0892-FF32-03
Copyright
Copyright © Materials Research Society 2006

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References

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