Extended Data Fig. 7: Electroluminescence versus graphene’s hot electron incandescence.
From: Electroluminescence and energy transfer mediated by hyperbolic polaritons
a, Sweep of the mid-infrared spectral emission of the TR1 device (inset) under electrical bias, measured via IR-SMS. b, Spectral flux at the HPhP resonance, marked by an asterisk in panel a, as a function of applied bias. Both experiments were performed at Vg = 0 V. The hollow grey triangles are the Planck law fit given by \(A{E}^{3}\,/[\exp (E\,/{k}_{B}{T}_{e})-1]\), in which A is a fitting constant, E = 192 meV is the polariton energy, and Te is the electron temperature given in Extended Data Table 2. A is determined by equating the spectral flux at Vds = 4.3 V to the value of the measured spectral flux at the same point. The magenta and grey curves are a second-order polynomial fit and a linear fit, respectively, corresponding to the data points. The inset shows the ratio of the measured spectral flux to that obtained from the Planck law fit. The measured spectral flux with increasing bias is about two times larger than that expected from incandescence in the bias range 6−8 V, thus precluding graphene’s incandescence as a possible source of the measured signal. Note that this fitting procedure represents a worst-case scenario, in which it is assumed that the measured mid-IR flux at a low value of bias (4.3 V) is equal to that of the incandescence flux and the evolution of the two fluxes is compared as a function of increasing bias.
