Dielectric Properties and Ion Transport in Layered MoS_{2} Grown by Vapor-Phase Sulfurization

TL;DR

This study investigates the dielectric and electronic properties of vapor-phase grown MoS₂ in capacitor structures, revealing mobile ions likely as OH⁻, and discusses implications for defects, interface states, and neuromorphic device applications.

Contribution

It provides new insights into ion transport, interface states, and dielectric properties of vapor-phase MoS₂, highlighting potential for ion-based plasticity in 2D devices.

Findings

Presence of interfacial silicon oxide confirmed

Mobile ions, likely OH⁻, interact with interface states

Dielectric constant of MoS₂ is 2.6 to 2.9 at 100 kHz

Abstract

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.