3 March 2011 Vertical composition variation in nominally uniform InGaN layers revealed by aberration-corrected STEM imaging
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Proceedings Volume 7939, Gallium Nitride Materials and Devices VI; 79391E (2011) https://doi.org/10.1117/12.889392
Event: SPIE OPTO, 2011, San Francisco, California, United States
Abstract
We have found composition variations along the growth direction within regions of nominally constant indium composition in InGaN light emitting diode structures grown by metal-organic chemical vapor deposition using atomic resolution Z-contrast imaging in a scanning transmission electron microscope (STEM). Within 60 nm thick nominally In0.01Ga0.99N layers, we found periodic enhancements in the indium concentration into 4 bands separated by 11 nm. Energy dispersive spectroscopy spectrum imaging confirmed that the higher intensity in the high angle annular dark field (HAADF) Z-contrast STEM images was in fact caused by locally higher indium concentration. We observed no lateral indium composition fluctuations.
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A. B. Yankovich, A. V. Kvit, X. Li, F. Zhang, V. Avrutin, H. Y. Liu, N. Izyumskaya, Ü. Özgür, H. Morkoç, P. M. Voyles, "Vertical composition variation in nominally uniform InGaN layers revealed by aberration-corrected STEM imaging", Proc. SPIE 7939, Gallium Nitride Materials and Devices VI, 79391E (3 March 2011); doi: 10.1117/12.889392; https://doi.org/10.1117/12.889392
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