The Effect of Substrate on the Electron Transport Properties of MoS$_{2}$ Field-Effect Transistors

Substrate plays an important role in the performance of field-effect transistors (FETs) with two-dimensional transition metal dichalcogenide (TMD) channels. In this work, we systematically study the transport properties of few-layer MoS$_{2}$ FETs consistently fabricated on various substrates including SiO$_{2}$, Al$_{2}$O$_{3}$, SiO$_{2}$ modified by octadecyltrimethoxysilane (OTMS) self-assembled monolayers (SAMs), and hexagonal boron nitride (hBN). Standard four-probe electrical transport measurement was carried out at temperatures ranging from 77 K to room temperature to understand the scattering mechanism. Surprisingly, the room temperature mobility extracted from devices on different substrates is nearly the same. In contrast, a substantially higher mobility is observed in MoS$_{2}$ devices on clean hBN substrates at low temperatures. The role of various sources of scattering originating from the substrate and the channel/substrate interface such as charged impurities, charge traps, surface roughness, and remote surface optical phonons will be discussed.