Tunable Current Transport in PdSe 2 via Layer‐by‐Layer Thickness Modulation by Mild Plasma

The thickness‐modulated phase transition from semi‐metallic (bulk) to semiconductor (a few layers) is the most unique property of pentagonal palladium diselenide (PdSe 2 ). Thus, precise thickness tailoring is essential to fully utilize its unique thickness‐dependent property for exotic device applications. Here, tunable current transport in PdSe 2 based field‐effect transistors (FETs) enabled by layer‐by‐layer thinning of PdSe 2 using mild SF 6 :N 2 plasma is presented. With this top‐down plasma‐etching method, the PdSe 2 layer thickness can be precisely modulated without structural degradation, which paves the way to realize the complete potential of PdSe 2 ‐based devices. By modifying the plasma power and exposure time, an atomic layer precision etching rate of 0.4 nm min −1 can be achieved. Atomic‐force microscopy, Raman spectroscopy, and secondary ion mass spectrometry confirm the uniform and complete removal of top layers of PdSe 2 flake over a large area without affecting remaining bottom layers. Electrical characterization of current transport in plasma‐thinned PdSe 2 FETs reveals excellent layer‐dependent conductivity similar to pristine PdSe 2 FETs. This simple but highly scalable and controllable plasma‐etching technique provides a promising way to fabricate PdSe 2 devices based on lateral heterostructures composed of different thicknesses PdSe 2 flakes to exploit strongly thickness‐dependent electronic structures.