Abstract To enhance the feasibility of 2-dimensional transition metal dichalcogenides (TMDCs) channels in future nano-electronic and optoelectronic devices, a top gate device structure fabricated with very-large-scale-integration compatible process is mandatory. High-κ dielectric ZrO₂ has been directly deposited on MoS₂ through low-temperature atomic layer deposition (ALD) without any surface protection layers. The uniform growth of ZrO₂ on MoS₂ was confirmed to be caused by the physical adsorption, resulting in the suppressed interfacial oxidation and the reduced damage of monolayer (1L) MoS₂ channel. Low thermal budget post-deposition annealing was found to be effective for reducing interfacial traps between ZrO₂ and MoS₂ interface, thus enhancing the device performances of 1L MoS₂ nMOSFETs. Low capacitance equivalent thickness (CET) of ZrO₂ of 2.3 nm has been achieved while maintaining decent device performance, indicating low-temperature ALD is promising for future TMDC top gate devices with a high-quality interface and thin CET.