Alloy fluctuations at dislocations in III-nitrides : dentification and impact on optical properties

Massabuau, F. C.-P. and Chen, P. and Rhode, S. L. and Horton, M. K. and O'Hanlon, T. J. and Kovács, A. and Zielinski, M. S. and Kappers, M. J. and Dunin-Borkowski, R. E. and Humphreys, C. J. and Oliver, R. A.; (2018) Alloy fluctuations at dislocations in III-nitrides : dentification and impact on optical properties. In: Proceedings Volume 10532, Gallium Nitride Materials and Devices XIII. Proceedings of SPIE - The International Society for Optical Engineering, 10532 . Society of Photo-Optical Instrumentation Engineers, USA, pp. 301-306. (https://doi.org/10.1117/12.2288211)

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Abstract

We investigated alloy fluctuations at dislocations in III-Nitride alloys (InGaN and AlGaN). We found that in both alloys, atom segregation (In segregation in InGaN and Ga segregation in AlGaN) occurs in the tensile part of dislocations with an edge component. In InGaN, In atom segregation leads to an enhanced formation of In-N chains and atomic condensates which act as carrier localization centers. This feature results in a bright spot at the position of the dislocation in the CL images, suggesting that non-radiative recombination at dislocations is impaired. On the other hand, Ga atom segregation at dislocations in AlGaN does not seem to noticeably affect the intensity recorded by CL at the dislocation. This study sheds light on why InGaN-based devices are more resilient to dislocations than AlGaN-based devices. An interesting approach to hinder non-radiative recombination at dislocations may therefore be to dope AlGaN with In.

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