Fig. 2: Photocurrent measurements under λ = 8.6 μm illumination at T = 7 K. | npj 2D Materials and Applications

Fig. 2: Photocurrent measurements under λ = 8.6 μm illumination at T = 7 K.

From: Infrared photodetection in graphene-based heterostructures: bolometric and thermoelectric effects at the tunneling barrier

Fig. 2

a Scheme of the photocurrent and \({{\rm {d}}}^{2}{I}_{{{{\rm{b}}}}}/{\rm {d}}{V}_{{{{\rm{b}}}}}^{2}\) measurements. b Spatial photocurrent map. Deviation of the spot from the symmetrical Gaussian shape is aberration due to a slightly oblique incidence of light on the lens but not the sample features. c Slice of the map at y = 30 μm and spot size extracted by fitting to Gaussian distribution. d Photocurrent as a function of bias and gate voltages. e Second derivative of Ib(Vb) as a function of bias and gate voltages. It’s clearly seen how the photocurrent repeats all \({{\rm {d}}}^{2}{I}_{{{{\rm{b}}}}}/{\rm {d}}{V}_{{{{\rm{b}}}}}^{2}\) features in details. f \({d}^{2}{I}_{{{{\rm{b}}}}}/d{V}_{{{{\rm{b}}}}}^{2}\) averaged over all gate voltages. g–i Slices of maps (d) and (e) at two different gate voltages: g Vgate = 0 V, h Vgate = −4 V and i at small bias Vb = 5 mV. Features at the energies of the phonon modes are marked by arrows on (d, e) and by vertical dashed lines on (f).

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