Dielectric Properties and Ion Transport in Layered MoS Grown by Vapor-Phase Sulfurization for Potential Applications in Nanoelectronics.

Electronic and dielectric properties of vapor-phase grown MoS have been investigated in metal/MoS/silicon capacitor structures by capacitance-voltage and conductance-voltage techniques. Analytical methods confirm the MoS layered structure, the presence of interfacial silicon oxide (SiO ) 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. Measurements under electric field stress indicate the existence of mobile ions in MoS that interact with interface states. On the basis of time-of-flight secondary ion mass spectrometry, we propose OH ions as probable candidates responsible for the observations. The dielectric constant of the vapor-phase grown MoS extracted from CV measurements at 100 kHz is 2.6 to 2.9. The present study advances the understanding of defects and interface states in MoS. It also indicates opportunities for ion-based plasticity in 2D material devices for neuromorphic computing applications.