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Bayesian Spectroscopy on Polarization Dependent Photoluminescence Spectra of Doubly‐Split Excitons in a Cu 2 O Thin‐Crystal Sandwiched by MgO Substrates
Author(s) -
Kiridoshi Arisa,
Aihara Shingo,
Arishima Syunshiro,
Yamashiro Tetsuya,
Mizumaki Masaichiro,
Iwamitsu Kazunori,
Akai Ichiro
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.201800136
Subject(s) - exciton , photoluminescence , spectroscopy , materials science , spectral line , tetragonal crystal system , polarization (electrochemistry) , crystal (programming language) , condensed matter physics , phonon , thin film , molecular physics , physics , crystallography , crystal structure , chemistry , optoelectronics , nanotechnology , quantum mechanics , astronomy , computer science , programming language
By using Bayesian spectroscopy, we studied polarization dependence of photoluminescence (PL) spectra in doubly‐split 1S yellow ortho‐excitons in a Cu 2 O thin‐crystal recrystallized in a small gap between paired MgO substrates. In these thin‐crystals, biaxial stresses are expected to be involved due to a small lattice mismatch between Cu 2 O and MgO. Under a planar‐isotropic biaxial stress, the cubic symmetry degrades to the tetragonal one in Cu 2 O, and subsequently, the ortho‐exciton state splits into two states having different symmetries. Consequently, the resonant PL intensities of the doubly‐split ortho‐excitons are expected to show different polarization dependencies. To elucidate such biaxial stress effect, we measured polarization dependence of the PL spectra at 4.2 K. Although resonant weak PL bands of the doubly‐split exciton states and their intense phonon sidebands co‐exist, we succeeded in decomposing to the respective spectral components by the Bayesian spectroscopy with a replica exchange Monte Carlo algorithm. As a result, it is found that the resonant PL band appearing on higher energy side shows hardly polarization dependence, whereas the resonant PL band appearing on lower energy side is further weak and shows noticeable polarization dependence. These results can be explained by the selection rule and polarization dependences on the transition matrix elements of quadrupole transitions of the doubly‐split ortho‐exciton states, and it clearly shows that the crystal symmetry degrades to D 4h by the isotropic biaxial stress involved in the Cu 2 O thin‐crystals.