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Temperature Dependence of Stokes Shifts of Excitons and Biexcitons in Al 0.61 Ga 0.39 N Epitaxial Layer
Author(s) -
Murotani Hideaki,
Ikeda Kazuki,
Tsurumaru Takuto,
Fujiwara Ryota,
Kurai Satoshi,
Miyake Hideto,
Hiramatsu Kazumasa,
Yamada Yoichi
Publication year - 2018
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201700374
Subject(s) - biexciton , exciton , delocalized electron , condensed matter physics , photoluminescence , excitation , spectroscopy , epitaxy , materials science , molecular physics , chemistry , physics , layer (electronics) , optoelectronics , nanotechnology , quantum mechanics , organic chemistry
Excitonic optical properties of an Al 0.61 Ga 0.39 N epitaxial layer are studied by using photoluminescence (PL) and PL excitation (PLE) spectroscopy. The peak structures due to the biexciton two‐photon and the exciton resonances are clearly observed in the PLE spectra of biexcitons up to 550 K. These observations enable the evaluation of the Stokes shifts of excitons and biexcitons as a function of temperature. The Stokes shifts of both excitons and biexcitons decrease with the increase in temperature up to 300 K, which originates from the gradual delocalization of excitons and biexcitons with the increasing temperature. At temperatures above 300 K, the Stokes shifts of both excitons and biexcitons are independent of the temperature. These observations suggest that the localization mechanism for excitons and biexcitons in AlGaN‐based systems cannot be explained by only the simple alloy disorder model, but there is a particular mechanism of exciton and biexciton localization in addition to the inhomogeneous broadening due to the alloy disorder.