Fig. 3

Electrical characteristics of devices based on photo-switchable superlattices. Transfer characteristics (I_DS–V_GS) of devices based on graphene and MoS₂ superlattices. I_DS is the drain current, and V_GS is the gate potential. a Schematics of the experiment. I_DS–V_GS characteristics are measured on: (1) A 2DM-based clean device; (2) after spin-coating of the spiro film; (3) after irradiation with a UV light over the whole flake, which triggers the SP→MC isomerization; (4) after green light irradiation over the whole flake, which triggers the MC→SP isomerization. Gold contacts are schematically drawn in yellow, the 2DM in dark gray; the substrate in blue; the SP layer in semi-transparent red; the MC layer in semi-transparent green. b Trace 1 (black): clean graphene, trace 2 (red): graphene covered by the SP layer, trace 3 (blue): graphene/MC after UV irradiation over the whole flake. The arrow highlights the negative shift in the threshold voltage accompanying the SP→MC isomerization, indicative of n-type doping. c Trace 4 (green): recovered graphene/SP after green light irradiation of the whole graphene surface. Traces 2 and 3 are replotted for clarity (dashed). d Trace 1 (black): clean MoS₂, trace 2 (red): MoS₂ covered by the SP layer, trace 3 (blue): MoS₂/MC after UV irradiation over the whole flake. e Trace 4 (green): the pristine MoS₂/SP trace can be recovered upon irradiation of the whole surface with green light. Traces 2 and 3 are replotted for clarity. Details about the UV and green light irradiation are given in the Methods section; the transfer curves were measured applying a drain source voltage V_DS = 10 mV for graphene (b, c) and V_DS = 100 mV for MoS₂ (d, e). Channel length L = 8.9 µm and width W = 1.0 µm (graphene); L = 1.8 µm, W = 3.3 µm (MoS₂)