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.
F. C.-P. Massabuau, P. Chen, S. L. Rhode, M. K. Horton, T. J. O'Hanlon, A. Kovács, M. S. Zielinski, M. J. Kappers, R. E. Dunin-Borkowski, C. J. Humphreys, and R. A. Oliver, "Alloy fluctuations at dislocations in III-nitrides: identification and impact on optical properties," Proc. SPIE 10532, Gallium Nitride Materials and Devices XIII, 105320R (Presented at SPIE OPTO: January 30, 2018; Published: 23 February 2018); https://doi.org/10.1117/12.2288211.
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Study of self-shadowing effect as a simple means to realize nanostructured thin films and layers with special attentions to birefringent obliquely deposited thin films and photo-luminescent porous silicon