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

TL;DR

This paper introduces a non-invasive photodelamination technique for 2D van der Waals semiconductors, enabling uniform monolayer production with preserved lattice quality and high electron mobility, advancing post-etching processing for electronics.

Contribution

The study demonstrates a low-power, ambient photodelamination method for selectively stripping excess layers in 2D semiconductors without damaging the lattice, improving wafer uniformity.

Findings

Fast etching rates of 0.3-0.8 μm/min at varied temperatures.

Preservation of lattice quality with defect density similar to pristine flakes.

High electron mobility up to 80 cm²/V·s in as-etched monolayers.

Abstract

Atomically thin two-dimensional (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, we report the observation of the energy funneling effect and ambient photodelamination phenomenon in inhomogeneous few-layer WS$_2$ flakes under low illumination fluencies down to several nW/$\mu$m$^{2}$ and its potential as a non-invasive post-etching strategy for selectively stripping the local excessive overlying islands. Photoluminescent tracking on the photoetching traces reveals relatively fast etching rates around $0.3-0.8\,\mu$m/min at varied temperatures and an activation energy of $1.7\,$eV. By using crystallographic and electronic characterization, we also confirm the non-invasive nature of the low-power photodelamination and the highly preserved lattice quality in the as-etched monolayer products, featuring a comparable average density of atomic defects (ca.$4.2\times 10^{13}\,$cm$^{-2}$) to pristine flakes and a high electron mobility up to $80\,$cm$^{2}\cdot$V$^{-1}\cdot$s$^{-1}$) at room temperature. This approach opens a non-invasive photoetching route for thickness uniformity management in 2D van der Waals semiconductor wafers for electronic applications.