Noninvasive Photodelamination of van der Waals Semiconductors for High-Performance Electronics.

Atomically thin 2D van der Waals semiconductors are promising candidate materials for post-silicon electronics. However, it remains challenging to attain completely uniform monolayer semiconductor wafers free of over-grown islands. Here, the observation of the energy-funneling effect and ambient photodelamination phenomenon in inhomogeneous few-layer WS2 flakes under low-illumination fluencies down to several nW µm-2 and its potential as a noninvasive atomic-layer etching strategy for selectively stripping the local excessive overlying islands are reported. Photoluminescent tracking on the photoetching traces reveals relatively fast etching rates of around 0.3-0.8 µm min-1 at varied temperatures and an activation energy of 1.7 eV. By using crystallographic and electronic characterization, the noninvasive nature of the low-power photodelamination and the highly preserved lattice quality are also confirmed in the as-etched monolayer products, featuring a comparable density of atomic defects (≈4.2 × 1013 cm-2 ) to pristine flakes and a high electron mobility of up to 80 cm2 V-1 s-1 at room temperature. This approach opens a noninvasive postetching route for thickness uniformity management in 2D van der Waals semiconductor wafers for electronic applications.