Band Tail States: Speed Bump or End of the Road for Two-Dimensional Semiconductors?
Abstract
We propose that the path to realizing the full potential of two-dimensional (2D) electronics lies in understanding and mastering their energy band tail states (BTS). Unlike silicon, which benefits from sharp band edges (Urbach energy E U ~ 10 meV), today's monolayer 2D semiconductors have rough band edges (E U ~ 100 meV) caused by spatial potential inhomogeneity. Comparing a physics-based electrical model to experiments, we demonstrate that BTS cause reduced effective mobility and "slow" transistor turn-on with excessive gate voltage in monolayer 2D transistors, which sets a fundamental limit for their energy-efficient operation. We also show that BTS effects in 2D transistors could be mitigated with higher gate capacitance, with strain engineering, and by using bilayer instead of monolayer 2D channels, as long as E U is reduced below ~ 50 meV. This work provides a theoretical framework and design guidelines to navigate these fundamental limits, and to enable successful integration of 2D semiconductors into low-power nanoelectronics.
Related
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BibTeX
@misc{han2026band,
title = {{Band Tail States: Speed Bump or End of the Road for Two-Dimensional Semiconductors?}},
author = {Zherui Han and Robert K. A. Bennett and Davide Donadio and Maritha A. Wang and Tara Peña and Mikaël Cassé and Martin Vanbrabant and Valeriya Kilchytska and Jean-Pierre Raskin and Eric Pop},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.10953},
eprint = {2610.10953},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.10953},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Band Tail States: Speed Bump or End of the Road for Two-Dimensional Semiconductors?
AU - Zherui Han
AU - Robert K. A. Bennett
AU - Davide Donadio
AU - Maritha A. Wang
AU - Tara Peña
AU - Mikaël Cassé
AU - Martin Vanbrabant
AU - Valeriya Kilchytska
AU - Jean-Pierre Raskin
AU - Eric Pop
PY - 2026
DA - 2026/10/07
PB - arXiv
DO - 10.48550/arxiv.2610.10953
UR - https://arxiv.org/abs/2610.10953
AB - We propose that the path to realizing the full potential of two-dimensional (2D) electronics lies in understanding and mastering their energy band tail states (BTS). Unlike silicon, which benefits from sharp band edges (Urbach energy E_ U ~ 10 meV), today's monolayer 2D semiconductors have rough band edges (E_ U ~ 100 meV) caused by spatial potential inhomogeneity. Comparing a physics-based electrical model to experiments, we demonstrate that BTS cause reduced effective mobility and "slow" transistor turn-on with excessive gate voltage in monolayer 2D transistors, which sets a fundamental limit for their energy-efficient operation. We also show that BTS effects in 2D transistors could be mitigated with higher gate capacitance, with strain engineering, and by using bilayer instead of monolayer 2D channels, as long as E_ U is reduced below ~ 50 meV. This work provides a theoretical framework and design guidelines to navigate these fundamental limits, and to enable successful integration of 2D semiconductors into low-power nanoelectronics.
ER -