Tunable Current Transport in PdSe2 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 (PdSe2). Thus, precise thickness tailoring is essential to fully utilize its unique thickness‐dependent property for exotic device applications. Here, tunable current transport in PdSe2 based field‐effect transistors (FETs) enabled by layer‐by‐layer thinning of PdSe2 using mild SF6:N2 plasma is presented. With this top‐down plasma‐etching method, the PdSe2 layer thickness can be precisely modulated without structural degradation, which paves the way to realize the complete potential of PdSe2‐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 PdSe2 flake over a large area without affecting remaining bottom layers. Electrical characterization of current transport in plasma‐thinned PdSe2 FETs reveals excellent layer‐dependent conductivity similar to pristine PdSe2 FETs. This simple but highly scalable and controllable plasma‐etching technique provides a promising way to fabricate PdSe2 devices based on lateral heterostructures composed of different thicknesses PdSe2 flakes to exploit strongly thickness‐dependent electronic structures. A highly selective, reproducible, and CMOS compatible plasma‐etching technique for uniform layer‐by‐layer thinning of PdSe2 is demonstrated. The transport properties of plasma‐thinned PdSe2‐based devices exhibit well‐matched transport behavior compared to pristine PdSe2 FETs. This plasma‐thinning technique provides a promising way to fabricate PdSe2‐based devices utilizing strong thickness‐dependent electronic structures.