Fig. 4: Temperature-dependent lateral transport and tunnelling current.

a, Tunnelling current in the 3L device without laser illumination at 100 mK (black) and 295 K (red). The logarithmic dependence in the \(\mathrm{ln}\left(|{I}_{\mathrm{G}}\text{|}/{V}_{\mathrm{G}}^{2}\right)\) scale with respect to −1/V_G for V_G < −1 V reveals no transition in the dark at low temperatures and a sharp transition at room temperature. In the inset, the tunnelling photocurrent at 100 mK (blue) is compared with the dark tunnelling current at room temperature, revealing a comparable trend in the Fowler–Nordheim regime (1/V_G < −0.2 V and a transition voltage of around 5 V for both cases. b, Lateral p-type transport for the 3L device at 100 mK (blue) and 295 K (violet). The thermal broadening due to Fermi–Dirac scaling with temperature induces a shift in the first-detectable subthreshold p-type signal³³, as further discussed in Supplementary Note 2. However, no substantial change in the subthreshold slope is detected. In the inset, the p-type subthreshold slopes (SSp) of the 3L (blue) and 6L (yellow) devices are shown. The sizeable difference in magnitude of \({\mathrm{SS}}_{\mathrm{p}}^{3{\mathrm{L}}}\) and \({\mathrm{SS}}_{\mathrm{p}}^{6{\mathrm{L}}}\) both at room and cryogenic temperatures is related to the increase in hole effective mass in InSe for a decreasing number of layers.