# Researchers build 2D MoS2 transistors using coal-derived carbon dot dielectrics

- Published: 2026-11-07 01:48 UTC
- Section: Machines & Making › Electronics
- Tags: carbon nanodots, equivalent oxide thickness, 2D electronics, top-gated transistor, molybdenum disulfide, atomic layer deposition, gate dielectric
- URL: https://realtech.media/news/rt-8a8cb151c1b9d88b82da008a_researchers_build_2d/

**Engineers used coal-derived carbon dots as a seed layer for atomic layer deposition, creating gate dielectrics with a 0.6-nanometre equivalent oxide thickness.**

![Researchers build 2D MoS2 transistors using coal-derived carbon dot dielectrics](https://realtech.media/media/2026/11/07c1d6655ddd321c.png)
*nature.com*

Engineers from the University of Illinois Urbana-Champaign and the National Energy Technology Laboratory have demonstrated top-gated two-dimensional transistors using carbon nanodots derived from bituminous coal, according to nature.com [1]. The researchers assembled these graphene-like dots into an atomically thin nucleation layer for the atomic layer deposition of hafnium dioxide onto molybdenum disulfide (MoS2) and graphene channels [1]. The resulting hybrid dielectric reached an equivalent oxide thickness (EOT) of 0.6 ± 0.1 nm, a leakage current density below 10⁻⁴ A·cm⁻², and a breakdown field of 28 MV·cm⁻¹ [1].

## Interfacial assembly and dielectric performance

Direct growth of high-κ gate dielectrics on two-dimensional materials is typically hindered by their chemically inert van der Waals surfaces, which lack dangling bonds to serve as nucleation centers [1]. Conventional seed layers often cause high interfacial roughness, decompose below 220 °C, or damage the underlying 2D channel [1]. To bypass these issues, the team applied carbon dots measuring 1 to 5 nm in diameter and approximately 0.4 nm in thickness from solution dispersions under mild conditions [1]. The carbon dots assembled into a dense monolayer that binds non-covalently without chemical hybridization, providing a thermal stability of at least 400 °C [1].

## Transistor characteristics and low-voltage logic

Top-gated MoS2 field-effect transistors built with the carbon dot/HfO2 dielectric bilayer showed a subthreshold swing approaching the thermionic limit of 60 mV·dec⁻¹ and a hysteresis below 30 mV [1]. The devices exhibited near-zero positive threshold voltages for enhancement-mode operation, with a narrow threshold distribution of 60 mV and bias-stress drift under 25 mV [1]. Leveraging this sub-nanometre EOT and interface stability, the authors fabricated multi-transistor logic circuits operating at a supply voltage of 0.5 V [1].

## Sources

1. [nature.com](https://www.nature.com/articles/s41467-026-78053-3)
2. [newswise.com](https://www.newswise.com/articles/coal-derived-carbon-nanodots-enable-next-generation-2d-electronics)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-8a8cb151c1b9d88b82da008a_researchers_build_2d/