Figure 3: Tunable photo-thermionic response. | Nature Communications

Figure 3: Tunable photo-thermionic response.

From: Photo-thermionic effect in vertical graphene heterostructures

Figure 3

(a,b) PC maps of the device shown in Fig. 1d measured with an interlayer bias voltage VB of (a) −0.6 V and (b) 0.6 V, and VG=0 V. The graphene flakes are outlined by black dotted lines and the WSe2 flake by solid orange lines, as in Fig. 1d. Scale bar, 3 μm. (ce) PC versus VB and VG measured on single Schottky barriers formed by (c) top or (d) bottom graphene and WSe2, as well as (e) double G/WSe2/G interfaces. The coloured circle (green, red and blue) in the upper right corner of each measurement corresponds to the position of the focused laser beam which are indicated on the PC maps (a,b). The black dashed line in e indicates where PC is null. All measurements are scaled to the same colour bar. Insets of c,d: side view of the heterostructure illustrating the generation and transport of hot carriers from one graphene flake to the other. Insets of e: band diagrams depicting the PTI effect in G/WSe2/G for VB<0 (left) and VB>0 (right). (f) PC versus VG taken from (e) at VB=0.6 V. Inset: band diagrams of the GB/WSe2 Schottky barrier at low (bottom) and high (top) VG illustrating the increase of PTI emission resulting from the lowering of ΦB. All measurements are performed at room temperature, with Ephoton=0.8 eV and P=110 μW.

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