Effect of Al₂O₃ Deposition on Performance of Top-Gated Monolayer MoS₂-Based Field Effect Transistor

Deposition of high- k dielectrics on two-dimensional MoS 2 is an important process for successful application of the transition-metal dichalcogenides in electronic devices. Here, we show the effect of H 2 O reactant exposure on monolayer (1L) MoS 2 during atomic layer deposition (ALD) of Al 2 O 3 . The results showed that the ALD-Al 2 O 3 caused degradation of the performance of 1L MoS 2 field effect transistors (FETs) owing to the formation of Mo–O bonding and trapping of H 2 O molecules at the Al 2 O 3 /MoS 2 interface. Furthermore, we demonstrated that reduced duration of exposure to H 2 O reactant and postdeposition annealing were essential to the enhancement of the performance of top-gated 1L MoS 2 FETs. The mobility and on/off current ratios were increased by factors of approximately 40 and 10 3, respectively, with reduced duration of exposure to H 2 O reactant and with postdeposition annealing.