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Spatial clustering of defect luminescence centers in Si-doped low resistivity Al0.82Ga0.18N

Kusch, Gunnar and Nouf-Allehiani, M. and Mehnke, Frank and Kuhn, Christian and Edwards, Paul R. and Wernicke, Tim and Knauer, Arne and Kueller, Viola and Naresh-Kumar, G. and Weyers, Markus and Kneissl, Michael and Trager-Cowan, Carol and Martin, Robert W. (2015) Spatial clustering of defect luminescence centers in Si-doped low resistivity Al0.82Ga0.18N. Applied Physics Letters, 107 (7). ISSN 0003-6951

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Abstract

A series of Si-doped AlN-rich AlGaN layers with low resistivities was characterized by a combination of nanoscale imaging techniques. Utilizing the capability of scanning electron microscopy to reliably investigate the same sample area with different techniques, it was possible to determine the effect of doping concentration, defect distribution, and morphology on the luminescence properties of these layers. Cathodoluminescence shows that the dominant defect luminescence depends on the Si-doping concentration. For lower doped samples, the most intense peak was centered between 3.36 eV and 3.39 eV, while an additional, stronger peak appears at 3 eV for the highest doped sample. These peaks were attributed to the (VIII-ON)2− complex and the VIII3− vacancy, respectively. Multimode imaging using cathodoluminescence, secondary electrons, electron channeling contrast, and atomic force microscopy demonstrates that the luminescence intensity of these peaks is not homogeneously distributed but shows a strong dependence on the topography and on the distribution of screw dislocations.