Dynamics of anomalous temperature-induced emission shift in MOCVD-grown (Al, In)GaN thin films

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We present a comprehensive study of the optical characteristics of (Al, In)GaN epilayers measured by photoluminescence (PL), integrated PL intensity, and time-resolved PL spectroscopy. For not only InGaN, but also AlGaN epilayers with large Al content, we observed an anomalous PL temperature dependence: (i) an "S-shaped" PL peak energy shift (decrease-increase-decrease) and (ii) an "inverted S-shaped" full width at half maximum (FWHM) change (increase-decrease-increase) with increasing temperature. Based on time-resolved FL, the S shape (inverted S shape) of the PL peak position (FWHM) as a function of temperature, and the much smaller PL intensity decrease in the temperature range showing the anomalous emission behavior, we conclude that strong localization of carriers occurs in InGaN and even in AlGaN with rather high Al content. We observed that the following increase with increasing Al content in AlGaN epilayers: (i) a Stokes shift between the PL peak energy and the absorption edge, (ii) a redshift of the emission with decay time, (iii) the deviations of the PL peak energy, FWHM, and PL intensity from their typical temperature dependence, and (iv) the corresponding temperature range of the anomalous emission behavior. This indicates that the band-gap fluctuation responsible for these characteristics is due to energy tail states caused by non-random inhomogeneous alloy potential variations enhanced with increasing Al content.
Publisher
MATERIALS RESEARCH SOCIETY
Issue Date
2000
Language
English
Article Type
Article; Proceedings Paper
Keywords

MULTIPLE-QUANTUM WELLS; RECOMBINATION DYNAMICS; LOCALIZED EXCITONS; INGAN SINGLE; ALXGA1-XN; PHOTOLUMINESCENCE; SUPERLATTICES; STATES; DIODES

Citation

MRS INTERNET JOURNAL OF NITRIDE SEMICONDUCTOR RESEARCH, v.5, pp.11 - 57

ISSN
1092-5783
URI
http://hdl.handle.net/10203/74032
Appears in Collection
PH-Journal Papers(저널논문)
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