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- Title
The Wannier-Mott Exciton, Bound Exciton, and Optical Phonon Replicas of Single-Crystal GaSe.
- Authors
Le, Long V.; Huong, Tran Thi Thu; Nguyen, Tien-Thanh; Nguyen, Xuan Au; Nguyen, Thi Huong; Cho, Sunglae; Kim, Young Dong; Kim, Tae Jung
- Abstract
We report the absorption and photoluminescence spectra of GaSe single crystals in the near-edge region. The temperatures explored the range from 17 to 300 K. Specifically, at a temperature of 17 K, the photoluminescence spectrum reveals an interesting phenomenon: the Wannier-Mott exciton separates into two states. These states are a triplet state with an energy of 2.103 eV and a singlet state with an energy of 2.109 eV. The energy difference between these two states is 6 meV. Furthermore, the bound exciton (BX) can be localized at an energy of 2.093 eV. It is worth noting that its phonon replicas (BX-nLO) can be clearly distinguished up to the fourth order. Interestingly, the energy gaps between these replicas exhibit a consistent spacing of 7 ± 0.5 meV. This intriguing finding suggests a high-quality crystalline structure as well as a strong coupling between the phonon and BX-nLO. Additionally, at low temperatures, both the ground state (n = 1) at 2.11 eV and the excited state (n = 2) at 2.127 eV of free excitons can be observed.
- Subjects
PHONONS; ENERGY levels (Quantum mechanics); BAND gaps; CRYSTAL structure; EXCITED states; X-ray absorption near edge structure
- Publication
Crystals (2073-4352), 2024, Vol 14, Issue 6, p539
- ISSN
2073-4352
- Publication type
Article
- DOI
10.3390/cryst14060539