Dual-gated bilayer graphene hot-electron bolometer

Journal name:
Nature Nanotechnology
Year published:
Published online


Graphene is an attractive material for use in optical detectors because it absorbs light from mid-infrared to ultraviolet wavelengths with nearly equal strength. Graphene is particularly well suited for bolometers—devices that detect temperature-induced changes in electrical conductivity caused by the absorption of light—because its small electron heat capacity and weak electron–phonon coupling lead to large light-induced changes in electron temperature. Here, we demonstrate a hot-electron bolometer made of bilayer graphene that is dual-gated to create a tunable bandgap and electron-temperature-dependent conductivity. The bolometer exhibits a noise-equivalent power (33 fW Hz–1/2 at 5 K) that is several times lower, and intrinsic speed (>1 GHz at 10 K) three to five orders of magnitude higher than commercial silicon bolometers and superconducting transition-edge sensors at similar temperatures.

At a glance


  1. Bilayer graphene device and typical optoelectronic response.
    Figure 1: Bilayer graphene device and typical optoelectronic response.

    a, Schematic of device geometry and electric-field-effect gating. b, Optical micrograph of a bilayer graphene device. Scale bar, 5 µm. For clarity, the image shows the sample before top-gate dielectric and metal deposition. c, Photoresponse of DGBLG. The sample is gated to a charge-neutral position with a displacement field of 0.45 V nm−1. Blue squares are the photoresponse ΔV. Red circles are the electrical resistance change ΔR =  ΔV/Idc.

  2. Dependencies of R and [Delta]V on Vtg and Vbg.
    Figure 2: Dependencies of R and ΔV on Vtg and Vbg.

    a, Two-dimensional map of R(Vtg,Vbg) measured in the dark. b, Two-dimensional map of ΔV(Vtg,Vbg) with a d.c. bias of 255 nA. c,d, One-dimensional cuts of R and ΔV through data in a and b. The two black cuts correspond to varying the average displacement field (varying the bandgap) while maintaining charge neutrality (n = 0). Others correspond to varying the charge density at fixed average displacement fields (fixed bandgap). e, Comparison of normalized R2 and ΔV with varying average displacement fields at charge neutrality, where . f, Comparison of normalized R2 and ΔV with varying charge density at a fixed average displacement field of 0.45 V nm−1, where Rn=0 = 30 k, ΔVn=0 = 28 µV. Measurements were carried out at a temperature of 6 K in cold helium gas.

  3. Comparison of photoresponse and electrical heating of DGBLG at charge neutrality with D = -0.65 V nm-1.
    Figure 3: Comparison of photoresponse and electrical heating of DGBLG at charge neutrality with D macr = −0.65 V nm−1.

    Optical and electrical measurements were performed simultaneously with d.c. and a.c. currents and photon illumination from 0.658 µm laser light. Left inset: optical (blue) and electrical (red) responses as a function of d.c. current at T = 5.16 K. We extract the slope of these traces near Idc = 0 and plot them as a function of temperature in the main panel. Right inset: data in log–log scale.

  4. Electrical heating of DGBLG at charge neutrality with D = 0.55 V nm-1.
    Figure 4: Electrical heating of DGBLG at charge neutrality with D macr = 0.55 V nm−1.

    ac, Temperature dependence of resistance R, derivative of resistance with power dR/dP and heat resistance Rh. Symbols are experimental data, and red lines are power-law fits. d, Heat conduction diagram for the device.

  5. Response speed of DGBLG HEB.
    Figure 5: Response speed of DGBLG HEB.

    Normalized photoresponse from pump–probe laser pulses as a function of delay tD at 4.55 K and 10 K with bias Idc = 185 nA. The sample is gated to charge neutrality with a displacement field of 0.45 V nm−1. Lines show best fits assuming exponential decay of hot-electron temperature Te with a thermal response time τ and considering a nonlinear Te dependence of graphene resistance. Solid line (red) and dot-dashed line (blue) are for τ = 0.25 ns and 0.1 ns, respectively.


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Author information


  1. Center for Nanophysics and Advanced Materials and Materials Research Science and Engineering Center, University of Maryland, College Park, Maryland 20742, USA

    • Jun Yan,
    • M-H. Kim,
    • A. B. Sushkov,
    • G. S. Jenkins,
    • M. S. Fuhrer &
    • H. D. Drew
  2. Department of Physics, University of Maryland, College Park, Maryland 20742, USA

    • Jun Yan,
    • M-H. Kim,
    • J. A. Elle,
    • A. B. Sushkov,
    • G. S. Jenkins,
    • H. M. Milchberg,
    • M. S. Fuhrer &
    • H. D. Drew
  3. Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA

    • J. A. Elle &
    • H. M. Milchberg


M.S.F. and H.D.D. conceived the project. J.Y. fabricated the devices and performed the transport measurements. M.H.K., J.Y., A.B.S. and G.S.J. conducted the photoresponse experiments. J.A.E. and H.M.M. assisted in the pump–probe measurements. J.Y., M.H.K., M.S.F. and H.D.D. analysed data and wrote the manuscript. All authors discussed and contributed to writing the manuscript.

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