Density functional theory—projected local density of states—based estimation of Schottky barrier for monolayer MoS2

One of the biggest challenges so far in implementing 2D materials in device applications is the formation of a high quality Schottky barrier. Here, we have conducted density functional theory simulations and employed the projected local density of states technique to study the Schottky contact formation between monolayer (ML) MoS2 with different metal electrodes (Mo, W, and Au). Electrode formation on ML MoS2 changes it from intrinsic to a doped material due to metallization, which creates issues in the formation of a good Schottky contact. Amongst the metals studied here, we observe that Mo tends to form the best Schottky barrier with ML MoS2 based on both the vertical and lateral Schottky barrier heights (0.13 eV for the vertical Schottky barrier and 0.1915 eV for the lateral Schottky barrier) and the built-in potential (0.0793 eV). As compared to Mo, Au forms a high-resistance ohmic contact with a much larger vertical barrier height of 0.63 ± 0.075 eV and a negligible built-in potential. It is thus observed that ML MoS2 is very susceptible to strain and pinning of the Fermi level due to metal junction formation. Thus, understanding both the vertical and horizontal Schottky barrier heights along with the built-in potential is critical for designing high performance 2D semiconductor devices.