Observation of quasi-steady dark excitons and gap phase in a doped semiconductor

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Main Authors: Mo, Shangkun, Bai, Yunfei, Wu, Chunlong, Cui, Xingxia, Mei, Guangqiang, Wan, Qiang, Li, Renzhe, Peng, Cao, Zhao, Keming, Qin, Dingkun, Yu, Shuming, Zhong, Hao, Wang, Xingzhe, Li, Enting, Li, Yiwei, Cao, Limin, Feng, Min, Meng, Sheng, Xu, Nan
Format: Preprint
Published: 2025
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author Mo, Shangkun
Bai, Yunfei
Wu, Chunlong
Cui, Xingxia
Mei, Guangqiang
Wan, Qiang
Li, Renzhe
Peng, Cao
Zhao, Keming
Qin, Dingkun
Yu, Shuming
Zhong, Hao
Wang, Xingzhe
Li, Enting
Li, Yiwei
Cao, Limin
Feng, Min
Meng, Sheng
Xu, Nan
author_facet Mo, Shangkun
Bai, Yunfei
Wu, Chunlong
Cui, Xingxia
Mei, Guangqiang
Wan, Qiang
Li, Renzhe
Peng, Cao
Zhao, Keming
Qin, Dingkun
Yu, Shuming
Zhong, Hao
Wang, Xingzhe
Li, Enting
Li, Yiwei
Cao, Limin
Feng, Min
Meng, Sheng
Xu, Nan
contents Exciton plays an important role in optics and optics-related behaviors and leads to novel correlated phases like charge order, exciton insulator, and exciton-polariton condensation. Dark exciton shows distinct properties from bright one. However, it cannot be directly detected by conventional optic measurements. The electronic modulation effect of dark excitons in quasi-equilibrium distribution, critical for electronic devices in working status, is still elusive. Here, using angle-resolved photoemission spectroscopy, we report creating, detecting, and controlling dark excitons in the quasi-equilibrium distribution in a doped semiconductor SnSe2. Surprisingly, we observe an excitonic gap phase, with a conduction band opening an anisotropic gap. Our results broaden the scope of dark excitons, extending their studies from the picosecond timescale in the ultrafast photoemission process to conditions occurring under quasi-equilibrium. We reveal the light-matter interaction in the engineering of electronic structures and provide a new way to realize the excitonic gap phase in semiconductors with large band gaps.
format Preprint
id arxiv_https___arxiv_org_abs_2507_08419
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Observation of quasi-steady dark excitons and gap phase in a doped semiconductor
Mo, Shangkun
Bai, Yunfei
Wu, Chunlong
Cui, Xingxia
Mei, Guangqiang
Wan, Qiang
Li, Renzhe
Peng, Cao
Zhao, Keming
Qin, Dingkun
Yu, Shuming
Zhong, Hao
Wang, Xingzhe
Li, Enting
Li, Yiwei
Cao, Limin
Feng, Min
Meng, Sheng
Xu, Nan
Materials Science
Mesoscale and Nanoscale Physics
Strongly Correlated Electrons
Exciton plays an important role in optics and optics-related behaviors and leads to novel correlated phases like charge order, exciton insulator, and exciton-polariton condensation. Dark exciton shows distinct properties from bright one. However, it cannot be directly detected by conventional optic measurements. The electronic modulation effect of dark excitons in quasi-equilibrium distribution, critical for electronic devices in working status, is still elusive. Here, using angle-resolved photoemission spectroscopy, we report creating, detecting, and controlling dark excitons in the quasi-equilibrium distribution in a doped semiconductor SnSe2. Surprisingly, we observe an excitonic gap phase, with a conduction band opening an anisotropic gap. Our results broaden the scope of dark excitons, extending their studies from the picosecond timescale in the ultrafast photoemission process to conditions occurring under quasi-equilibrium. We reveal the light-matter interaction in the engineering of electronic structures and provide a new way to realize the excitonic gap phase in semiconductors with large band gaps.
title Observation of quasi-steady dark excitons and gap phase in a doped semiconductor
topic Materials Science
Mesoscale and Nanoscale Physics
Strongly Correlated Electrons
url https://arxiv.org/abs/2507.08419