TY - JOUR
T1 - Study of thin films polarity of Group III nitrides
AU - Dovidenko, K.
AU - Oktyabrsky, S.
AU - Narayan, J.
AU - Razeghi, M.
N1 - Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 1999
Y1 - 1999
N2 - Thin films of GaN grown by MOCVD on (0001) sapphire were studied by transmission electron microscopy in order to correlate the observed extended defects with crystal polarity of the films. We propose relatively simple and unambiguous method of polarity determination for wurtzite group III nitrides based on the dependence of the intensity of diffracted beams upon thickness of the specimen. Due to the dynamic scattering by polar structure, the convergent beam electron diffraction patterns lose inversion symmetry and become in fact fingerprints of the structure carrying information about crystal polarity. In this study, we have used the thinnest regions of the specimens (< 15 nm) and multiple diffraction spots in high-symmetry orientation for polarity determination. The films were found to have Ga-polar surfaces, either being unipolar, or containing thin (10-30 nm in diameter) columnar inversion domains (IDs) of N-polarity. The occurrence of IDs was correlated with specific types of dislocation distribution in the films.
AB - Thin films of GaN grown by MOCVD on (0001) sapphire were studied by transmission electron microscopy in order to correlate the observed extended defects with crystal polarity of the films. We propose relatively simple and unambiguous method of polarity determination for wurtzite group III nitrides based on the dependence of the intensity of diffracted beams upon thickness of the specimen. Due to the dynamic scattering by polar structure, the convergent beam electron diffraction patterns lose inversion symmetry and become in fact fingerprints of the structure carrying information about crystal polarity. In this study, we have used the thinnest regions of the specimens (< 15 nm) and multiple diffraction spots in high-symmetry orientation for polarity determination. The films were found to have Ga-polar surfaces, either being unipolar, or containing thin (10-30 nm in diameter) columnar inversion domains (IDs) of N-polarity. The occurrence of IDs was correlated with specific types of dislocation distribution in the films.
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U2 - 10.1557/s109257830000332x
DO - 10.1557/s109257830000332x
M3 - Article
AN - SCOPUS:3442879938
VL - 4
SP - 6d
JO - MRS Internet Journal of Nitride Semiconductor Research
JF - MRS Internet Journal of Nitride Semiconductor Research
SN - 1092-5783
IS - SUPPL. 1
ER -