Abstract
2D semiconductors like Molybdenum disulfide (MoS2) still have issues in forming good metal electrode (Schottky and Ohmic) especially for mono layer (ML) to few layers thick due to strain and metallization issues. Here, we explore a 2D semi-metal, titanium disulfide (TiS2), for making different types of contacts with ML MoS2 using density functional theory (DFT). It is observed that ML TiS2 induces ML MoS2 to become p-type with a doping density of 3.85 × 1017 cm−3 which becomes larger with thicker TiS2. Thus, TiS2 can thus be utilized as a variable contact material ohmic if the MoS2 is p-type and as Schottky if the MoS2 is n-type with a Schottky barrier height ranging from 0.3 to 1.35 eV. One of the important results from the study is that compared to a traditional metal–MoS2 in a TiS2–MoS2 contact the bandgap is preserved where in contrast, a traditional metal contact metalizes the monolayer MoS2 and fill its bandgap with states. Hence, a clear path forward to make pristine contacts is to use 2D semi-metals in conjunction with 2D semiconductors.
Highlights
In recent years, molybdenum disulfide (MoS2), one of the transition metal dichalcogenide monolayers (TMDC), has attracted significant attention and has been explored for a variety of applications in a vast range of fields[1,2,3]
Some groups have utilized encapsulation technique, the MoS2 mobility can be preserved by using hexagonal boron nitride (h-BN) nano sheets to enclose the MoS2 sheet[19,20]
The “Methods” section describes the density functional theory (DFT) techniques used for this research
Summary
Molybdenum disulfide (MoS2), one of the transition metal dichalcogenide monolayers (TMDC), has attracted significant attention and has been explored for a variety of applications in a vast range of fields[1,2,3]. Another interesting finding from our study is that the Schottky barrier height for the TiS2 contact and ML MoS2 changes by varying the doping type and concentration of MoS2. By using the projected local device density of states (PLDOS) analysis, we have extracted the barrier heights of TiS2–MoS2 (ML) contacts at different doping type and concentrations along with different TiS2 thickness.
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