Reducing Plasma-Induced Damage in 2D Transition Metal Dichalcogenide Heterostructures through Optimized Plasma-Enhanced Atomic Layer Deposition

In recent years, two-dimensional transition-metal dichalcogenides (2D TMDs) have emerged as attractive alternative channel materials for next-generation field-effect transistors. Despite significant advances in integrating 2D TMDs into electronic devices, challenges remain, such as fabrication-induced damage, particularly from plasma processes commonly employed in device integration such as etching, cleaning, and deposition. This work systematically identifies and minimizes the sources of plasma-induced damage associated with plasma-enhanced atomic layer deposition (PEALD), particularly during PEALD of TMD films onto CVD-grown TMD substrates for contact applications. On the basis of Raman, photoluminescence, and X-ray photoelectron spectroscopy, damage caused by Ar/H 2 S plasmas to monolayer WSe 2 was reduced by removing Ar from the plasma, reducing the plasma power, and increasing the process chamber pressure. The optimized plasma parameters were subsequently applied to develop an alternative PEALD process for polycrystalline Nb x W 1- x S 2, leading to enhanced preservation of mono-to-few-layer WSe 2 within PEALD Nb x W 1- x S 2 /MOCVD WSe 2 heterostructures, as shown by charge carrier mobility measurements and Raman spectroscopy. The understanding gained from this work provides broadly applicable strategies for reducing plasma-induced damage in 2D materials, paving the way for more robust plasma processing techniques for integration of 2D materials in high-performance heterostructure-based electronic devices.