Study of the band alignment between atomic-layer-deposited high-κ dielectrics and MoS₂ film

In this study, we determined the energy-band alignment of various amorphous high-κ dielectrics (Al₂O₃, HfO₂, ZrO₂, and TiO₂) that were deposited on a molybdenum disulfide (MoS2) film through atomic layer deposition by using high-resolution X-ray photoelectron spectroscopy. The uniformity and continuity of the MoS₂ films were inspected by physical characterizations. The roughness of MoS₂ film deposited by chemical vapor deposition was evaluated using atomic force microscopy. Moreover, cross-sectional transmission electron microscopy images confirmed that all high-κ dielectrics were uniformly and continuously deposited on the MoS₂ film, leading to superior high-κ dielectric-MoS₂ stacks. An abrupt interface between the high-κ dielectrics and MoS₂ film was also observed. Finally, the valance and conduction band offsets between the Al₂O₃, HfO₂, ZrO₂, and TiO₂ and the MoS₂ film interface were measured to be 3.14, 1.81, 1.56, and 0.18 eV and 2.36, 1.77, 1.88, and 1.68 eV, respectively. Our study demonstrated the direct deposition of numerous commonly used high-κ dielectrics on top of a MoS₂ film. This top-down scheme is very useful for applying two-dimensional materials to complementary metal-oxide-semiconductor field-effect-transistor circuits.