Fig. 2: Characterizations of the vdW metal-semiconductor interface.
From: Wafer-scale and universal van der Waals metal semiconductor contact
a Cross-sectional scanning electron microscopy (SEM) image of WSe2/PPC/Au tri-layer structure, purple dashed line represents WSe2. b Cross-sectional high-resolution transmission electron microscopy (HRTEM) image of the WSe2/Au vdW interface after PPC layer decomposed. Atomic sharp and clean metal-semiconductor interface is observed with a vdW gap of ~0.3 nm. c The schematic of atomic force microscopy (AFM) sample preparation for characterizing the interface quality in larger area. The as-fabricated Cr/WSe2 interface is decoupled by mechanically peeling-off the Cr electrodes, and the bottom surface of Cr electrode could be flipped for AFM measurement. d AFM characterization of Cr bottom surface (flipped after peeling), demonstrating a small root-mean square (RMS) of 0.16 nm. e AFM characterization of WSe2 top surface after peeling-off the Cr electrode, with RMS of 0.39 nm.
