High carrier mobility in monolayer CVD-grown MoS2 through phonon suppression

Abstract

Mobility engineering is one of the most important challenges that determine the optoelectronic performance of two-dimensional (2D) materials. So far, charged-impurity scattering and electrical-contact barriers have been suppressed through high-κ dielectrics and seamless contact engineering, giving rise to carrier-mobility improvement in exfoliated 2D semiconducting MoS₂. Here we demonstrate a facile and scalable technique to effectively suppress both Coulomb scattering and electron–phonon scattering via the HfO₂ overlayer, resulting in a large mobility improvement in CVD-grown monolayer MoS₂, in excess of 60 cm² V⁻¹ s⁻¹. Surface passivation and suppression of Coulomb scattering can partially contribute to the mobility increase. Interestingly, we correlate the mobility increase with phonon quenching through Raman and temperature-dependent mobility measurements. The experimental method is facile, industrially scalable, and renders phonon engineering an additional leverage towards further improvements in 2D semiconductor mobility and device performance.