High Mobility Ambipolar MoS2 Field-Effect Transistors: Substrate and Dielectric Effects

TL;DR

This study investigates how substrate and dielectric materials influence charge carrier mobility in multilayer MoS2 transistors, revealing significant mobility enhancements on PMMA due to dielectric effects.

Contribution

It demonstrates the impact of substrate and dielectric choice on mobility in multilayer MoS2 transistors, highlighting the role of dielectric environment in mobility enhancement.

Findings

Mobility on SiO2 is 30-60 cm2/Vs, mostly unipolar n-type.

Mobility on PMMA increases with thickness, reaching ~470 cm2/Vs.

Dielectric environment significantly affects charge transport in MoS2.

Abstract

We fabricate MoS2 field effect transistors on both SiO2 and polymethyl methacrylate (PMMA) dielectrics and measure charge carrier mobility in a four-probe configuration. For multilayer MoS2 on SiO2, the mobility is 30-60 cm2/Vs, relatively independent of thickness (15-90 nm), and most devices exhibit unipolar n-type behavior. In contrast, multilayer MoS2 on PMMA shows mobility increasing with thickness, up to 470 cm2/Vs (electrons) and 480 cm2/Vs (holes) at thickness ~50 nm. The dependence of the mobility on thickness points to a long-range dielectric effect of the bulk MoS2 in increasing mobility.