Toolbox of Advanced Atomic Layer Deposition Processes for Tailoring Large-Area MoS Thin Films at 150 °C.

Two-dimensional MoS is a promising material for applications, including electronics and electrocatalysis. However, scalable methods capable of depositing MoS at low temperatures are scarce. Herein, we present a toolbox of advanced plasma-enhanced atomic layer deposition (ALD) processes, producing wafer-scale polycrystalline MoS films of accurately controlled thickness. Our ALD processes are based on two individually controlled plasma exposures, one optimized for deposition and the other for modification. In this way, film properties can be tailored toward different applications at a very low deposition temperature of 150 °C. For the modification step, either H or Ar plasma can be used to combat excess sulfur incorporation and crystallize the films. Using H plasma, a higher degree of crystallinity compared with other reported low-temperature processes is achieved. Applying H plasma steps periodically instead of every ALD cycle allows for control of the morphology and enables deposition of smooth, polycrystalline MoS films. Using an Ar plasma instead, more disordered MoS films are deposited, which show promise for the electrochemical hydrogen evolution reaction. For electronics, our processes enable control of the carrier density from 6 × 10 to 2 × 10 cm with Hall mobilities up to 0.3 cm V s. The process toolbox forms a basis for rational design of low-temperature transition metal dichalcogenide deposition processes compatible with a range of substrates and applications.