Supression of charge impurities in haffnium oxide capped MoS₂

Atomically thin two-dimensional transition metal dichalcogenides offers wide range of applications thanks to its optical and electrical tunability. In this, the gate dielectrics play an important role in tuning the carrier concentration which impacts the optical and electrical properties. Here, we study the influence of gate dielectric on electrical properties of MoS2. We measure and compare the field effect mobility as a function of temperature in MoS2 and hafnium capped MoS2 devices. These measurements give insight into the dominant scattering mechanism in both type devices. We observe suppression of both, impurity scattering as well as phonon scattering in hafnium oxide encapsulated MoS2 device compared to uncapped MoS2 device. When the hafnium oxide encapsulated MoS2 device is further cooled down to lower temperatures, we observe conductance oscillations. We attribute these conductance oscillations to quantum interference due to phase coherence electron transport. Such oscillations are absent in uncapped MoS2 device. Suppressed impurity scattering and the observed quantum interference in encapsulated MoS2 devices indicates that these effects are induced by presence of hafnium oxide. Our work opens new possibilities of exploring quantum phenomenon in encapsulated 2D TMDC devices.