Large array fabrication of high performance monolayer MoS2 photodetectors

Large array fabrication of high quality photodetectors derived from synthetically grown monolayer transition metal dichalcogenides is highly desired and important for a wide range of nanophotonic applications. We present here large array fabrication of monolayer MoS₂ photodetectors on sapphire substrates through an efficient process, which includes growing large scale monolayer MoS₂ via chemical vapor deposition (CVD) and multi-step optical lithography for device patterning and high quality metal electrode fabrication. In every measured device, we observed the following universal features: (i) negligible dark current ( I_dark≤10 fA), (ii) sharp peaks in photocurrent at ∼1.9 eV and ∼2.1 eV attributable to the optical transitions due to band edge excitons, and (iii) a rapid onset of photocurrent above ∼2.5 eV peaked at ∼2.9 eV due to an excitonic absorption originating from the van Hove singularity of MoS₂. We observe a low (≤300%) device-to-device variation of photoresponsivity. Furthermore, we observe a very fast DC time response of ∼0.5 ms, which is two orders of magnitude faster than other reported CVD grown 1L-MoS₂ based photodetectors. The combination of large-array device fabrication, high sensitivity, and high speed offers great potential for applications in photonics.