a Optical image of two fabricated WSe2/SnSe2 devices. It is possible to distinguish the two flakes for each junction, the overlap region and the Pd contacts to the two sides of the heterostructure. For flakes sufficiently large it is possible to deposit four contacts, so to be able to characterize both the internal WSe2 FET and the heterojunction device. b SEM image of a final device with highlighted cutline for thickness estimation. c AFM profile of the WSe2 flake taken along the red cutline shown in the SEM image. The presented devices have been fabricated with 10-nm-thick WSe2 flakes.