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Indium incorporation in InGaN/GaN quantum wells grown on m ‐plane GaN substrate and c ‐plane sapphire
Author(s) -
Lai K. Y.,
Paskova T.,
Wheeler V. D.,
Chung T. Y.,
Grenko J. A.,
Johnson M. A. L.,
Udwary K.,
Preble E. A.,
Evans K. R.
Publication year - 2012
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201127345
Subject(s) - indium , cathodoluminescence , sapphire , quantum well , materials science , optoelectronics , diffraction , wavelength , substrate (aquarium) , transmission electron microscopy , epitaxy , optics , laser , luminescence , physics , nanotechnology , oceanography , layer (electronics) , geology
InGaN/GaN quantum wells (QWs) grown at identical conditions on m ‐plane GaN and c ‐plane sapphire substrates were characterized by several techniques, aiming to clarify the reason for different emission wavelengths often observed in similar LED structures with m ‐ and c ‐plane surface orientations. Cathodoluminescence (CL) spectra of m ‐plane QWs revealed shorter wavelength and no blueshift with increasing CL probe current in accordance with previous reports. Relative indium compositions were estimated by high‐resolution X‐ray diffraction to be 5.1 and 13.9% for m ‐plane and c ‐plane QWs, respectively. Cross‐sectional transmission electron microscopy images revealed that the well widths of the m ‐plane QWs were noticeably thicker than those of the c ‐plane QWs. The lower indium compositions and thicker well widths of the m ‐plane QWs indicated that different indium incorporation and diffusion occurred in the structures grown on the GaN substrate, which is attributed to its surface off‐cut toward [0001] and the higher thermal conductivity with respect to that of sapphire.