Figure 3:

(a) ${\text{S}}_{\text{C}}^{\prime }$ images acquired at V_BG as indicated. (b) ${\text{S}}_{\text{C}}^{\prime }$ and S_C as a function of V_BG acquired at the locations of the corresponding symbols in a)iii) and Fig. 2e)iii). (c) Line cuts across the tellurene device showing the topography (top) and ${\text{S}}_{\text{C}}^{\prime }$ and S_C at values of V_BG as indicated, taken from the location of the dashed line in a)ii) and Fig. 2e)ii). Dashed lines in b) and c) are a guide to the eye at ${\text{S}}_{\text{C}}^{\prime }=0\hspace{0.17em}\text{V}$. (d) Spatially resolved map of the local carrier equivalence voltage. (e) Line cut taken along the dashed line in d) showing a variation of V_BG > 33 V across the device.