Toolbox of Advanced Atomic Layer Deposition Processes for Tailoring Large-Area MoS2 Thin Films at 150 °C

Two-dimensional MoS2 is a promising materialfor applications,including electronics and electrocatalysis. However, scalable methodscapable of depositing MoS2 at low temperatures are scarce.Herein, we present a toolbox of advanced plasma-enhanced atomic layerdeposition (ALD) processes, producing wafer-scale polycrystallineMoS(2) films of accurately controlled thickness. Our ALDprocesses are based on two individually controlled plasma exposures,one optimized for deposition and the other for modification. In thisway, film properties can be tailored toward different applicationsat a very low deposition temperature of 150 & DEG;C. For the modificationstep, either H-2 or Ar plasma can be used to combat excesssulfur incorporation and crystallize the films. Using H-2 plasma, a higher degree of crystallinity compared with other reportedlow-temperature processes is achieved. Applying H-2 plasmasteps periodically instead of every ALD cycle allows for control ofthe morphology and enables deposition of smooth, polycrystalline MoS2 films. Using an Ar plasma instead, more disordered MoS2 films are deposited, which show promise for the electrochemicalhydrogen evolution reaction. For electronics, our processes enablecontrol of the carrier density from 6 x 10(16) to 2x 10(21) cm(-3) with Hall mobilitiesup to 0.3 cm(2) V-1 s(-1). The process toolbox forms a basis for rational design of low-temperaturetransition metal dichalcogenide deposition processes compatible witha range of substrates and applications.

Automated summary

This study presents an advanced plasma-enhanced ALD process for depositing wafer-scale polycrystalline MoS2 films with controlled thickness at low temperatures, which is promising for applications in electronics and electrocatalysis.