Nitride Dielectric Environments to Suppress Surface Optical Phonon Dominated Scattering in High‐Performance Multilayer MoS2 FETs

Abstract

The ultrathin channel in 2D semiconductors, although playing host to several interesting properties, also renders strong interactions (scattering) of charge carriers with the surrounding medium. The over‐arching dominance of surface (interfacial) optical phonons in 2D charge transport and engineering ideal nitride‐based dielectric environments for large performance gains is reported. Charge transport in MoS2 field effect transistors (FETs) fabricated on three conventional substrates, SiO2, Al2O3, and HfO2, is contrasted with a newly introduced, CMOS‐compatible nitride‐based dielectric: aluminum nitride (AlN) by employing semi‐classical models which account for charged impurity, surface optical phonon, and intrinsic phonon scattering. Unlike previous reports focused on charge impurity scattering, this work presents a new paradigm of utilizing high optical phonon energies intrinsic to “stiff” nitride bonds. This results in substantially lower surface optical phonon scattering in 2D FETs which directly influences peak field effect (FE) mobility, high field mobility degradation, and temperature‐dependent mobility. Leveraging on these insights, high‐performance sulfur‐passivated MoS2 FETs with an optimum all‐nitride environment (hexagonal boron nitride/MoS2/AlN) are demonstrated with FE mobility up to 72.8 cm2 V−1 s−1. This work is envisioned to address important issues in design of dielectric environments for a host of applications based on 2D materials.