Tunable Current Transport in PdSe₂ via Layer‐by‐Layer Thickness Modulation by Mild Plasma

Abstract

Abstract 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.