Monolayer (ML) transition metal dichalcogenides are novel, gapped two-dimensional materials with unique electrical and optical properties. Toward device applications, we consider MoS2 layers on dielectrics, in particular in this work, the effect of vacancies on the electronic structure. In densityfunctional based simulations, we consider the effects of near-interfaceOvacancies in the oxide slab, andMoor S vacancies in the MoS2 layer. Band structures and atom-projected densities of states for each system and with differing oxide terminations were calculated, as well as those for the defect-free MoS2-dielectrics system and for isolated dielectric layers for reference. Among our results, we find that with O vacancies, both the Hf-terminated HfO2-MoS2 system, and the O-terminated and H-passivated Al2O3-MoS2 systems appear metallic due to doping of the oxide slab followed by electron transfer into the MoS2, in manner analogous to modulation doping. The n-type doping of MLMoS2 by high-k oxides with oxygen vacancies then is experimentally demonstrated by electrically and spectroscopically characterizing back-gated MLMoS2 field effect transistors encapsulated by oxygen deficient alumina and hafnia.
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All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering