Stable Al₂O₃ Encapsulation of MoS₂‐FETs Enabled by CVD Grown h‐BN

Abstract

Abstract Molybdenum disulfide (MoS 2 ) has great potential as a two‐dimensional semiconductor for electronic and optoelectronic application, but its high sensitivity to environmental adsorbents and charge transfer from neighboring dielectrics can lead to device variability and instability. Aluminum oxide (Al 2 O 3 ) is widely used as an encapsulation layer in (opto)‐electronics, but it leads to detrimental charge transfer n‐doping to MoS 2 . Here, this work reports a scalable encapsulation approach for MoS 2 field‐effect transistors (FETs) where hexagonal boron nitride (h‐BN) monolayers are employed as a barrier layer in‐between each of the Al 2 O 3 and MoS 2 interfaces. These devices exhibit a significant reduction of charge transfer, when compared to structures without h‐BN. This benefit of h‐BN in the gate stack is confirmed by ab initio density functional theory calculations. In addition, the devices with h‐BN layers show very low hysteresis even under ambient operating conditions.