  Two-dimensional materials such as graphene and transition metal
dichalcogenides (TMDs) are ideal candidates to create ultra-thin electronics
suitable for flexible substrates. Although optoelectronic devices based on TMDs
have demonstrated remarkable performance, scalability is still a significant
issue. Most devices are created using techniques that are not suitable for mass
production, such as mechanical exfoliation of monolayer flakes and patterning
by electron-beam lithography. Here we show that large-area MoS2 grown by
chemical vapor deposition and patterned by photolithography yields highly
sensitive photodetectors, with record shot-noise-limited detectivities of 8.7 X
10^14 Jones in ambient condition and even higher when sealed with a protective
layer. These detectivity values are higher than the highest values reported for
photodetectors based on exfoliated MoS2. We study MoS2 devices with gold
electrodes and graphene electrodes. The devices with graphene electrodes have a
tunable band alignment and are especially attractive for scalable ultra-thin
flexible optoelectronics.
