Study of band alignment at MoS_2/SiO_2 interfaces grown by pulsed laser deposition method

摘要

We report on the large-area and high-quality growth of single- to few-monolayer thick MoS_2 thin films on oxidized Si (100) substrates via the pulsed laser deposition method. Our Raman, x-ray photoelectron spectroscopic, and FE-SEM measurements confirmed that atomically thin MoS_2 layers are highly uniform and are stoichiometric. We found a type-Ⅰ band alignment at the MoS2/SiO_2 heterointerfaces through photoemission spectroscopic valence-band measurements. The valence- and conduction band offset (VBO and CBO) at the 1L MoS_2/SiO_2 interface was observed to be 3.91 and 2.96 +0.05 eV, respectively. The values of VBO and CBO increase up to 4.15 and 3.56 ± 0.05 eV, respectively, with an increase in the MoS_2 layer number. This observation can be attributed to the shift of the Mo-4d_(z~2) orbitals due to interlayer coupling for thicker MoS_2 films, reducing its bandgap, resulting in an increment in VBO and CBO values.