Effect of substrate on the growth and properties of MoS2 thin films grown by plasma-enhanced atomic layer deposition

Abstract

Plasma-enhanced atomic layer deposition was used to grow molybdenum disulfide films using (tBuN)2(NMe2)2Mo and a remote H2S-Ar plasma as coreactants on three different substrates: thermal oxide on silicon, c-plane sapphire, and epitaxial c-plane GaN on sapphire. Depositions were carried out at 250 °C. The substrates’ effect on the growth of MoS2 was investigated through resonance Raman spectroscopy, x-ray photoelectron spectroscopy, and atomic force microscopy. In addition, transmission electron microscopy was performed on films deposited on electron-transparent silicon nitride membranes. Films of 2H-MoS2 were deposited with atomic-level control of thickness under the deposition conditions studied. By analyzing the resonance Raman spectrum, it was found that higher degrees of crystallinity could be achieved on GaN or Al2O3 substrates compared to thermally oxidized silicon.