  Electronic and dielectric properties of vapor-phase grown MoS_{2} have been
investigated in metal/MoS_{2}/silicon capacitor structures by
capacitance-voltage and conductancevoltage techniques. Analytical methods
confirm the MoS_{2} layered structure, the presence of interfacial silicon
oxide (SiO_{x}) and the composition of the films. Electrical characteristics in
combination with theoretical considerations quantify the concentration of
electron states at the interface between Si and a 2.5 - 3 nm thick silicon
oxide interlayer between Si and MoS_{2}. Measurements under electric field
stress indicate the existence of mobile ions in MoS_{2} that interact with
interface states. Based on time-offlight secondary ion mass spectrometry, we
propose OH^{-} ions as probable candidates responsible for the observations.
The dielectric constant of the vapor-phase grown MoS_{2} extracted from CV
measurements at 100 KHz is in the range of 2.6 to 2.9. The present study
advances the understanding of defects and interface states in MoS_{2}. It also
indicates opportunities for ion-based plasticity in 2D material devices for
neuromorphic computing applications.
