Fig. 2: Thickness-dependent electrical measurement of WSe₂ transistors with vdW-integrated and evaporated Au electrodes.

a–c, I_ds−V_gs transfer curves of WSe₂ with different thicknesses (3 layers in a, 7 layers in b, and 12 layers in c) using vdW Au electrodes, where p-type behavior is consistently observed. d–f I_ds−V_gs transfer curves of WSe₂ with different thicknesses (3 layers in d, 7 layers in e, and 12 layers in f) using conventional deposited Au electrodes, where p-type, bipolar, and n-type behaviors are observed in d, e, and f, respectively. The V_ds bias voltage is 0.01 V (black), 0.1 V (red), 0.5 V (blue), and 1 V (brown) throughout a–f. g The current ratio between I_−50V (I_ds at V_g = −50 V) and I_50V (I_ds at V_g = 50 V) as a function of WSe₂ thickness. For devices with vdW electrodes, large I_−50V/I_50V ratio >10³ is observed, suggesting the consistent p-type behavior, regardless of the channel thickness. For devices with conventional evaporated Au electrodes, I_−50V/I_50V is decreased with increasing body thickness, where a p-type to n-type transition is clearly observed. The V_ds bias voltage in g is fixed at 500 mV.