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

Conference · Sat Jul 01 04:00:00 EDT 2000

OSTI ID:20104624

Cho, Y H; Gainer, G H; Lam, J B; Song, J J; Yang, W; Jhe, W

The authors 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, they 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 PL, 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, the authors conclude that strong localization of carriers occurs in InGaN and even in AlGaN with rather high Al content. They 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.

• Research Organization: Oklahoma State Univ., Stillwater, OK (US)
• OSTI ID: 20104624
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM NITRIDES
CHEMICAL VAPOR DEPOSITION
EXPERIMENTAL DATA
GALLIUM NITRIDES
INDIUM NITRIDES
OPTICAL PROPERTIES
PHOTOLUMINESCENCE
TEMPERATURE DEPENDENCE
THIN FILMS