Cuprous iodide (CuI) is an emerging wide-bandgap semiconductor of superior optical and transport properties. In particular, CuI shows high stability and large oscillator strength of free excitons that are of great advantage for optoelectronic applications. However, thin films of CuI reported so far have not been genuine single crystals, containing a sizable density of impurity and defect. Here, we demonstrate a dramatic improvement in the quality of CuI films grown by molecular beam epitaxy on a lattice-matched InAs substrate. The film is revealed to be in a single-crystal structure with high lattice coherence and an atomically flat surface. The low-temperature photoluminescence spectra exhibit extremely sharp emission from free excitons and much-suppressed emission from trapped states. The high-quality CuI films realized in the present study will not only facilitate the device application of CuI films but also provide unprecedented functionalities in halide semiconductors at the atomically sharp heterointerfaces.
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Heteroepitaxial growth of wide bandgap cuprous iodide films exhibiting clear free-exciton emission
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4 January 2021
Research Article|
January 05 2021
Heteroepitaxial growth of wide bandgap cuprous iodide films exhibiting clear free-exciton emission
S. Inagaki;
S. Inagaki
1
Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo
, Bunkyo-ku, Tokyo 113-8656, Japan
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M. Nakamura
;
M. Nakamura
a)
2
RIKEN Center for Emergent Matter Science (CEMS)
, Wako 351-0198, Japan
a)Author to whom correspondence should be addressed: masao.nakamura@riken.jp
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Y. Okamura;
Y. Okamura
1
Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo
, Bunkyo-ku, Tokyo 113-8656, Japan
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M. Ogino;
M. Ogino
1
Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo
, Bunkyo-ku, Tokyo 113-8656, Japan
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Y. Takahashi;
Y. Takahashi
1
Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo
, Bunkyo-ku, Tokyo 113-8656, Japan
2
RIKEN Center for Emergent Matter Science (CEMS)
, Wako 351-0198, Japan
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L. C. Peng
;
L. C. Peng
2
RIKEN Center for Emergent Matter Science (CEMS)
, Wako 351-0198, Japan
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X. Z. Yu
;
X. Z. Yu
2
RIKEN Center for Emergent Matter Science (CEMS)
, Wako 351-0198, Japan
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Y. Tokura
;
Y. Tokura
1
Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo
, Bunkyo-ku, Tokyo 113-8656, Japan
2
RIKEN Center for Emergent Matter Science (CEMS)
, Wako 351-0198, Japan
3
Tokyo College, University of Tokyo
, Bunkyo-ku, Tokyo 113-8656, Japan
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M. Kawasaki
M. Kawasaki
1
Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo
, Bunkyo-ku, Tokyo 113-8656, Japan
2
RIKEN Center for Emergent Matter Science (CEMS)
, Wako 351-0198, Japan
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a)Author to whom correspondence should be addressed: masao.nakamura@riken.jp
Appl. Phys. Lett. 118, 012103 (2021)
Article history
Received:
November 09 2020
Accepted:
December 13 2020
Citation
S. Inagaki, M. Nakamura, Y. Okamura, M. Ogino, Y. Takahashi, L. C. Peng, X. Z. Yu, Y. Tokura, M. Kawasaki; Heteroepitaxial growth of wide bandgap cuprous iodide films exhibiting clear free-exciton emission. Appl. Phys. Lett. 4 January 2021; 118 (1): 012103. https://doi.org/10.1063/5.0036862
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