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arXiv · 2503.16234

Quasiparticle gap renormalization driven by internal and external screening in a WS$_2$ device

Chakradhar Sahoo·Yann in 't Veld·Alfred J. H. Jones·Zhihao Jiang·Greta Lupi·Paulina E. Majchrzak·Kimberly Hsieh·Kenji Watanabe·Takashi Taniguchi·Philip Hofmann·Jill A. Miwa·Yong P. Chen·Malte Rösner·Søren Ulstrup
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Abstract

The electronic band gap of a two-dimensional semiconductor within a device architecture is sensitive to variations in screening properties of adjacent materials in the device and to gate-controlled doping. Here, we employ micro-focused angle resolved photoemission spectroscopy to separate band gap renormalization effects stemming from environmental screening and electron-doping during \textit{in situ} gating of a single-layer WS$_{2}$ device. The WS$_{2}$ is supported on hBN and contains a section that is exposed to vacuum and another section that is encapsulated by a graphene contact. We directly observe the doping-induced semiconductor-metal transition and band gap renormalization in the two sections of WS$_2$. Surprisingly, a larger band gap renormalization is observed in the vacuum-exposed section than in the graphene-encapsulated - and thus ostensibly better screened - section of the WS$_2$. Using $GW$ calculations, we determine that intrinsic screening due to stronger doping in vacuum exposed WS$_2$ exceeds the external environmental screening in graphene-encapsulated WS$_2$.

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Chakradhar Sahoo, Yann in 't Veld, Alfred J. H. Jones, Zhihao Jiang, Greta Lupi, Paulina E. Majchrzak, Kimberly Hsieh, Kenji Watanabe, Takashi Taniguchi, Philip Hofmann, Jill A. Miwa, Yong P. Chen, Malte Rösner, Søren Ulstrup. 2025-03-20. Quasiparticle gap renormalization driven by internal and external screening in a WS$_2$ device. https://doi.org/10.1103/yllv-5zx7

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