Doping-Induced Dipole Effects for Barrier-Free P-Type MoS2–Metal Contacts

This study investigated the effect of substitutional doping on the electrostatics and contact resistance of MoS ${}_{{2}} -$ metal Schottky contacts through first-principles simulations. The introduction of dopants induced interface dipole charges, significantly reducing the Schottky barrier height ( $\varphi _{\text {B}}$ ). As a representative example, Nb doping in MoS2 effectively lowered the p-type Schottky barriers. The delta-function approximation was employed to model the dipole charge and determine the physical relationship between the doping concentration (NA) and $\varphi _{\text {B}}$ reduction in monolayer- and multilayer-doped MoS2–metal contacts. Simulations based on this model and the Schottky theory revealed that dipole-induced barrier lowering can reduce contact resistance by several orders of magnitude, achieving values as low as $24\Omega \cdot \mu $ m for a p-type MoS ${}_{{2}} -$ metal contact with a NA of $10^{{14}}$ cm ${}^{-{2}}$ and an intrinsic $\varphi _{\text {B}}$ of 0.1 eV. These findings highlight doping as a transformative approach for achieving low-resistance Ohmic contacts for high-performance two-dimensional field-effect transistors.