Impact of CVD chemistry on band alignment at the MoS2/SiO2 interface

Reliable knowledge of energy alignment of electronic bands at interfaces of few layered Molybdenum Disulfide (MoS2) is crucial for designing MoS2 based electronic devices. In this work, we have applied internal photoemission spectroscopy (IPE) to characterize this band alignment. MoS2 films grown on SiO2(50 nm)/Si using two different methods have been analyzed by IPE to determine the energy position of the semiconductor valence band (VB) relative to the reference level of the insulator conduction band (CB). We found that changing the MoS2 growth method from Vapor Phase Reaction (VPR) of MoO3 and sulfur, to Solid Precursor Film (SPF) of sulfurized AHM-NaOH spin coated MoS2 film, results in significant (≈600 meV) enhancement in the electron barrier. Such effects are ascribed to the interaction of hydroxy groups from NaOH and AHM promoters with the SiO2 surface leading to interface dipole modification.