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Polarity determination of crystal defects in zincblende GaN by aberration-corrected electron microscopy

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Xiu, Huixin 
Fairclough, Simon 
Gundimeda, Abhiram 
Kappers, Menno 
Wallis, David 


Aberration-corrected scanning transmission electron microscopy techniques are used to study the bonding configuration between gallium cations and nitrogen anions at defects in metalorganic vapour-phase epitaxy-grown cubic zincblende GaN on vicinal (001) 3C-SiC/Si. By combining high-angle annular dark-field and annular bright field imaging, the orientation and bond polarity of planar defects, such as stacking faults and wurtzite inclusions, were identified. It is found that the substrate miscut direction towards one of the 3C-SiC ⟨110⟩ in-plane directions is correlated with the crystallographic [1-10] in-plane direction and that the {111} planes with zone axis parallel to the miscut have a Ga-polar character, whereas the {111} planes in the zone perpendicular to the miscut direction have N-polarity. The polarity of {111}-type stacking faults is maintained in the former case by rotating the coordination of Ga atoms by 180° around the ⟨111⟩ polar axes and in the latter case by a similar rotation of the coordination of the N atoms. The presence of small amounts of the hexagonal wurtzite phase on Ga-polar {111} planes and their total absence on N-polar {111} planes is tentatively explained by the preferential growth of wurtzite GaN in the [0001] Ga-polar direction under non-optimised growth conditions.



51 Physical Sciences, 5104 Condensed Matter Physics

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Journal of Applied Physics

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American Institute of Physics
Engineering and Physical Sciences Research Council (EP/N01202X/1)
Engineering and Physical Sciences Research Council (EP/R01146X/1)
This work was enabled through financial support by the EPSRC through grant no EP/R01146X/1 “Fundamental studies of zincblende nitride structures for optoelectronic applications”. H. Xiu would like to thank China Scholarship Council and Shanghai Pujiang Program 22PJD046 for sponsoring her academic visit to the University of Cambridge. D. J. Wallis would like to thank the support of EPSRC through grant no. EP/N01202X/2.