The energy-band alignment at molybdenum disulphide and high-k dielectrics interfaces

Energy-band alignments for molybdenum disulphide (MoS2) films on high-k dielectric oxides have been studied using photoemission spectroscopy. The valence band offset (VBO) at monolayer MoS2/Al2O3 (ZrO2) interface was measured to be 3.31 eV (2.76 eV), while the conduction-band offset (CBO) was 3.56 eV (1.22 eV). For bulk MoS2/Al2O3 interface, both VBO and CBO increase by ∼0.3 eV, due to the upwards shift of Mo 4dz2 band. The symmetric change of VBO and CBO implies Fermi level pinning by interfacial states. Our finding ensures the practical application of both p-type and n-type MoS2 based complementary metal-oxide semiconductor and other transistor devices using Al2O3 and ZrO2 as gate materials.