Transition metal dichalcogenides (TMDs) are promising for next-generation electronic and optoelectronic device applications. However, the development of a viable TMD device technology requires an effective strategy for making low-resistance contacts to these materials. In addition, large-area synthesis of low-defect TMD crystals is essential for transforming basic device studies into commercial products. Here, we show large-area synthesis of monolayer (ML) MoS2 using chemical vapor deposition (CVD) with electron mobility of ∼64cm2/V.s at room temperature. We performed contact engineering through a combination of work function engineering and effective n-type doping of MoS2 using engineered sub-stoichiometric HfOx. Our results indicate significant reduction of the contact resistance to ∼480Ω.μm without degrading key transistor properties such as subthreshold swing (∼125mV/dec), mobility (∼64cm2/V.s), and ION/IOFF ratio (>106).