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28 March 2024 |
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High-energy exciton transitions in quasi-two-dimensional cadmium chalcogenide nanoplatelets | Roman B. Vasiliev
; Alexander I. Lebedev
; Elizabeth P. Lazareva
; Natalia N. Shlenskaya
; Vladimir B. Zaytsev
; Alexei G. Vitukhnovsky
; Yuanzhao Yao
; Kazuaki Sakoda
; | Date: |
27 Mar 2017 | Abstract: | Semiconductor nanoparticles of cadmium chalcogenides are known to exhibit
pronounced thickness-dependent $E_0$ series of exciton transitions at the
$Gamma$ point of the Brillouin zone (BZ). In this work, we report an
experimental evidence for high-energy series of exciton transitions, which
originates from BZ points different from the $Gamma$ point, in the family of
cadmium chalcogenide quasi-2D nanoplatelets (NPLs). Intensive UV absorption
bands demonstrating a pronounced size effect are observed for CdTe, CdSe, and
CdS NPLs in addition to the $E_0$ exciton bands in the visible region. These
new bands are attributed to transitions analogous to the $E_1$, $E_1+Delta_1$,
and $E_2$ series observed in bulk crystals. First-principles DFT calculations
of the electronic structure and absorption spectra support this explanation and
show that the main contribution to these optical transitions comes from $X$ and
$M$ points of the 2D BZ, which originate from $L$ and $X$ points of the 3D BZ.
At the same time, the $E_0$ series of transitions at the $Gamma$ point is well
described by the multiband effective-mass model. The observation of the UV
exciton bands reveals tunable optical properties of cadmium chalcogenide NPLs
in UV spectral region, which may be interesting for practical applications. | Source: | arXiv, 1703.8960 | Services: | Forum | Review | PDF | Favorites |
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