<p>The relentless pursuit of smaller, faster nanoelectronics concentrates intense heat at nanometer scales, threatening performance and reliability. Yet directly mapping this heat from nonequilibrium hot electrons has remained elusive. Here we introduce the non-contact force technique that directly images hot-electron temperature distributions in operando devices. Using a bimodal atomic force microscope with sideband modulation, we harness frequency mixing to greatly boost sensitivity to hot-electron forces while suppressing parasitic electrostatic signals. This enables a thermal force microscope that visualizes hot electrons in the nanoconstriction of a silicon channel. Quantitative analysis reveals that thermal-fluctuation-induced force from hot electrons (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">$\Delta {T}_{e} \sim 700\,{{{\rm{K}}}}$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">Δ</mi> <msub> <mrow> <mi>T</mi> </mrow> <mrow> <mi>e</mi> </mrow> </msub> <mo>~</mo> <mn>700</mn> <mspace width="0.25em" /> <mi mathvariant="normal">K</mi> </math></EquationSource> </InlineEquation>) significantly exceed indirect effects from lattice heating (<InlineEquation ID="IEq2"> <EquationSource Format="TEX">$\Delta {T}_{L} \sim 3\,{{{\rm{K}}}}$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">Δ</mi> <msub> <mrow> <mi>T</mi> </mrow> <mrow> <mi>L</mi> </mrow> </msub> <mo>~</mo> <mn>3</mn> <mspace width="0.25em" /> <mi mathvariant="normal">K</mi> </math></EquationSource> </InlineEquation>) or permittivity changes. At a 5 nm tip–sample gap, this pressure reaches ~3 bar, sufficient to drive substantial electro-thermo-mechanical effects. These results open a powerful route to probing hot-electron dynamics in working nanodevices and inform electro–thermal co-design strategies for post-Moore nanoelectronics.</p>

Thermal Force Imaging of Hot Electrons in Operando Nanodevices

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2026年4月9日

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Weikang Lu,
Ziyi Xu,
Hewan Zhang,
Svend Age Biehs,
Achim Kittel,
Ludi Qin,
Xue Gong,
Huanyi Xue,
Yanru Song,
Zhengyang Zhong,
Shiyou Chen,
Kun Ding,
Wei Lu,
Zhenghua An

摘要

The relentless pursuit of smaller, faster nanoelectronics concentrates intense heat at nanometer scales, threatening performance and reliability. Yet directly mapping this heat from nonequilibrium hot electrons has remained elusive. Here we introduce the non-contact force technique that directly images hot-electron temperature distributions in operando devices. Using a bimodal atomic force microscope with sideband modulation, we harness frequency mixing to greatly boost sensitivity to hot-electron forces while suppressing parasitic electrostatic signals. This enables a thermal force microscope that visualizes hot electrons in the nanoconstriction of a silicon channel. Quantitative analysis reveals that thermal-fluctuation-induced force from hot electrons ( $\Delta {T}_{e} \sim 700\,{{{\rm{K}}}}$ $Δ T_{e} ~ 700 K$ ) significantly exceed indirect effects from lattice heating ( $\Delta {T}_{L} \sim 3\,{{{\rm{K}}}}$ $Δ T_{L} ~ 3 K$ ) or permittivity changes. At a 5 nm tip–sample gap, this pressure reaches ~3 bar, sufficient to drive substantial electro-thermo-mechanical effects. These results open a powerful route to probing hot-electron dynamics in working nanodevices and inform electro–thermal co-design strategies for post-Moore nanoelectronics.