Atomic-layer soft plasma etching of MoS(2)

Transition from multi-layer to monolayer and sub-monolayer thickness leads to the many exotic properties and distinctive applications of two-dimensional (2D) MoS(2). This transition requires atomic-layer-precision thinning of bulk MoS(2) without damaging the remaining layers, which presently remains elusive. Here we report a soft, selective and high-throughput atomic-layer-precision etching of MoS(2) in SF(6) + N(2) plasmas with low-energy (<0.4 eV) electrons and minimized ion-bombardment-related damage. Equal numbers of MoS(2) layers are removed uniformly across domains with vastly different initial thickness, without affecting the underlying SiO(2) substrate and the remaining MoS(2) layers. The etching rates can be tuned to achieve complete MoS(2) removal and any desired number of MoS(2) layers including monolayer. Layer-dependent vibrational and photoluminescence spectra of the etched MoS(2) are also demonstrated. This soft plasma etching technique is versatile, scalable, compatible with the semiconductor manufacturing processes, and may be applicable for a broader range of 2D materials and intended device applications.