Titanium disulfide as Schottky/ohmic contact for monolayer molybdenum disulfide
Junsen Gao, Manisha Gupta
Abstract
Abstract 2D semiconductors like Molybdenum disulfide (MoS 2 ) 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 (TiS 2 ), for making different types of contacts with ML MoS 2 using density functional theory (DFT). It is observed that ML TiS 2 induces ML MoS 2 to become p-type with a doping density of 3.85 × 10 17 cm −3 which becomes larger with thicker TiS 2 . Thus, TiS 2 can thus be utilized as a variable contact material ohmic if the MoS 2 is p-type and as Schottky if the MoS 2 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–MoS 2 in a TiS 2 –MoS 2 contact the bandgap is preserved where in contrast, a traditional metal contact metalizes the monolayer MoS 2 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.