Hot-Carrier Distribution Spectroscopy by Transconductance in Two-Dimensional Field-Effect Transistors
Abstract
The transconductance gm = dID/dVG of a field-effect transistor (FET) is conventionally read as a proxy for carrier density. We show that it is instead a spectroscopic probe of the carrier distribution: because gm weights the spectral current j(E) by the gate-voltage derivative ∂ f(E)/∂ VG and integrates over energy, it is sensitive to the \emph{shape} of f(E), not merely its integrated weight n. We develop an energy-resolved transport framework for two-dimensional (2D) FETs and, within a gate-independent spectral-kernel approximation, derive the decomposition gm = gm(n) + gm(α) into the conventional density-modulation term gm(n) and a distribution-shape-driven term gm(α). The latter, obtained as the residual after subtracting the smooth density-modulation background from the measured gm, exhibits a characteristic anomalous peak at a gate voltage VGpk. This peak has no counterpart in equilibrium transport and \emph{cannot be explained by carrier density modulation alone}. With the spectral kernel calibrated, the peak position and height -- extracted from standard DC/lock-in gm sweeps -- constrain the hot-carrier energy E0, spectral width σ, and generation threshold nc, realizing a steady-state, all-electrical spectroscopy of the carrier distribution. An optional time-resolved extension further recovers the carrier relaxation time τ from the transient response following a pump excitation, establishing the 2D FET as a distribution-function spectrometer that requires no optical readout.
Versions
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BibTeX
@misc{wakabayashi2026hotcarrier,
title = {{Hot-Carrier Distribution Spectroscopy by Transconductance in Two-Dimensional Field-Effect Transistors}},
author = {Katsunori Wakabayashi},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2607.15578},
eprint = {2607.15578},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.15578},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Hot-Carrier Distribution Spectroscopy by Transconductance in Two-Dimensional Field-Effect Transistors
AU - Katsunori Wakabayashi
PY - 2026
DA - 2026/08/20
PB - arXiv
DO - 10.48550/arxiv.2607.15578
UR - https://arxiv.org/abs/2607.15578
AB - The transconductance g_m = dI_D/dV_G of a field-effect transistor (FET) is conventionally read as a proxy for carrier density. We show that it is instead a spectroscopic probe of the carrier distribution: because g_m weights the spectral current j(E) by the gate-voltage derivative ∂ f(E)/∂ V_G and integrates over energy, it is sensitive to the \emph{shape} of f(E), not merely its integrated weight n. We develop an energy-resolved transport framework for two-dimensional (2D) FETs and, within a gate-independent spectral-kernel approximation, derive the decomposition g_m = g_m^(n) + g_m^(α) into the conventional density-modulation term g_m^(n) and a distribution-shape-driven term g_m^(α). The latter, obtained as the residual after subtracting the smooth density-modulation background from the measured g_m, exhibits a characteristic anomalous peak at a gate voltage V_G^pk. This peak has no counterpart in equilibrium transport and \emph{cannot be explained by carrier density modulation alone}. With the spectral kernel calibrated, the peak position and height -- extracted from standard DC/lock-in g_m sweeps -- constrain the hot-carrier energy E_0, spectral width σ, and generation threshold n_c, realizing a steady-state, all-electrical spectroscopy of the carrier distribution. An optional time-resolved extension further recovers the carrier relaxation time τ from the transient response following a pump excitation, establishing the 2D FET as a distribution-function spectrometer that requires no optical readout.
ER -