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

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${}_2$.

31 pages, 12 figures (4 figures in main text and 8 figures in supporting information)

References in corpus (12)

• 2D materials and van der Waals heterostructures
• Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor
• Light-emitting diodes by bandstructure engineering in van der Waals heterostructures
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• Electronic Structure of Epitaxial Single-Layer MoS${}_2$
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• Band structures of plasmonic polarons
• Two-dimensional plasmonic polarons in n-doped monolayer MoS2
• Accessing the spectral function of in operando devices by angle-resolved photoemission spectroscopy
• Probing excitons with time-resolved momentum microscopy
• k-resolved ultrafast light-induced band renormalization in monolayer WS${}_2$ on graphene

Cited by in corpus (1)

• Persistence of charge ordering instability to Coulomb engineering in the excitonic insulator candidate TiSe${}_2$