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Solid-state thermometry via ionic-electronic coupling in two-dimensional heterostructures

Summary

Monolayer MoS2 field-effect transistors with van der Waals bimetallic thiophosphate (ABP2X6) top-gate dielectrics use thermally activated cation migration to modulate channel conductance, enabling compact solid-state thermometry with roughly 1-2 degC resolution, fast electronic readout, and sub-nanojoule readout energy in about one square micrometer footprint, supported by electrical characterization and complementary molecular dynamics with a tailored ReaxFF description.

Methods

Primary source: papers/Sen_Nature_Sensors_2026_galley.pdf (Nature Sensors; galley shows author queries in places).

Materials and crystals. Synthesis and chemical vapor transport growth protocols for representative ABP2X6 crystals (including multi-day two-zone furnace schedules with iodine transport agent), plus Raman, powder XRD, XPS, AFM, SEM, and EDS characterization as reported.

Device fabrication. Monolayer MoS2 on 25 nm Al2O3; e-beam lithography and SF6 RIE to pattern channels; mechanical exfoliation of 2D dielectrics onto channels; second lithography for source, drain, and top-gate electrodes; e-beam evaporation of Ni/Au contacts; dual-gated underlapped geometry.

Electrical measurements. Semi-automated probe station (Formfactor 11000) with Keysight B1500A parameter analyzer. Representative bias example from the manuscript: top-gate sweep -6 V to +6 V at fixed back-gate 3 V and drain 1 V; channel width 1 um. Transfer sweeps, sweep-range and sweep-rate studies, ambient temperature sweeps, time-resolved threshold tracking, and related analyses used to link hysteresis and on-off ratio to ion migration.

Reactive MD (supporting mechanism). A ReaxFF parametrization for Li-In-P-S was developed using DFT reference data (including elastic properties of beta-Li3PS4 and orthorhombic InPS4 from Materials Project structures, energy-strain fits, Birch-Murnaghan bulk modulus). Molecular dynamics simulations (Supplementary figures in the article) are used alongside experiment to support thermally activated Li+, Cu+, or Ag+ transport and extracted barriers and mobilities.

1 — MD application (atomistic dynamics). LAMMPS ReaxFF molecular dynamics in PBC supercells; NVT/NPT equilibration per Supplement (fs time step, ps/ns duration, Berendsen or Nose–Hoover thermostat on ion-transport runs). N/A on this one-page blurb: full atom counts. Gate bias −6 V to +6 V in ## Methods is a laboratory electric field on FETs; N/A to MD E-field in the ReaxFF summary. N/A — NPT Parrinello barostat details in this blurb. N/A — replica or metadynamics.

2 — Force-field training. Li–In–P–S ReaxFF fit to DFT (Materials Project geometries, Birch–Murnaghan bulk modulus, strain traces).

3 — Static QM / DFT in training — as above. 4 — Review — N/A.

Findings

  • ABP2X6-gated MoS2 FETs show n-type behavior with large on-off ratio; dual-sweep top-gate operation yields counterclockwise hysteresis and sweep-direction-dependent subthreshold slope consistent with mobile ions rather than ferroelectric switching alone.
  • Minor hysteresis loops under reduced sweep range and sweep-rate-dependent on-off ratio support diffusion-limited, history-dependent ion motion in the layered dielectric.
  • Current on-off ratio increases with temperature under fixed sweep conditions, consistent with thermally activated ion migration.
  • Combined experiment and MD analysis (including Arrhenius-style interpretation in the paper) ties device-level thermal sensitivity to ionic-electronic coupling in vdW thiophosphates.

  • Reported sensor metrics in the abstract include roughly 1-2 degC resolution, sub-nanojoule readout energy, and ~1 um2 footprint for the demonstrated platform.

  • Corpus honesty / outlook: Galley (Sen_Nature_Sensors_2026_galley.pdf); VOR-level reconciliation for any voltage/K-dependent figure; caveat in ## Limitations on ionic drift and sweep rate.

Limitations

Galley PDF may differ from final pagination; ionic devices can show sensitivity to sweep protocol and ambient exposure.

Relevance to group

Adri van Duin co-authors the ReaxFF parametrization and MD supporting ion-transport interpretation.

Citations and evidence anchors

DOI: 10.1038/s44460-026-00034-2.