Large array fabrication of high performance monolayer MoS2 photodetectors

Abstract

have contributed equally to this work.Scalable fabrication of high quality photodetectors derived from synthetically grown monolayer transition metal dichalcogenides is highly desired and important for wide range of nanophotonics applications. We present here scalable fabrication of monolayer MoS 2 photodetectors on sapphire substrates through an efficient process, which includes growing large scale monolayer MoS 2 via chemical vapor deposition (CVD), and multi-step optical lithography for device patterning and high quality metal electrodes fabrication. In every measured device, we observed the following universal features: (i) negligible dark current (I dark 10f A); (ii) sharp peaks in photocurrent at ∼1.9eV and ∼2.1eV attributable to the optical transitions due to band edge excitons; (iii) a rapid onset of photocurrent above ∼2.5eV peaked at ∼2.9eV due to an excitonic absorption originating from the van Hove singularity of MoS 2 . We observe low ( 300%) device-to-device variation of photoresponsivity. Furthermore, we observe very fast rise time ∼0.5 ms, which is three orders of magnitude faster than other reported CVD grown 1L-MoS 2 based photodetectors. The combination of scalable device fabrication, ultra-high sensitivity and high speed offer a great potential for applications in photonics.Atomically thin monolayer two-dimensional (2D) transition-metal dichalcogenides (TMDs) are attractive materials for next-generation nanoscale optoelectronic applications and have gained tremendous interest in wide range of fields.1-4 TMDs demonstrate several extraordinary properties that make TMDs very attractive for optical, electrical and opto-electronic applications. First, 2D confinement, direct band-gap nature 5 , large surfaceto-volume ratio 6 , and weak screening of charge carriers enhance the light-matter interactions 5,7-10 in these materials that lead to extraordinarily high absorption. Second, strong light-matter interaction creates electron-hole (e-h) pairs and forms two-body bound states, known as excitons (a hydrogenic entity made of an e-h pair).

Tailoring of Silver Nanocubes with Optimized Localized Surface Plasmon in a Gap Mode for a Flexible MoS2 Photodetector

“…Surprisingly, the photocurrent was drastically increased to about 0.91 µA at 3 V with an incident power of 46 nW after the loading of Ag nanocubes. This is about one order of magnitude higher than most of the photodetectors based on MoS 2 films, and also substantially superior to the PDs modified with nanospheres or nanowires . Compared to the pristine MoS 2 ‐based PDs, 19‐fold enhancement has been achieved for the Ag nanocube‐decorated device.…”

2D Transition Metal Dichalcogenide Thin Films Obtained by Chemical Gas Phase Deposition Techniques

“…Utilizing the same synthesis method, a photoresponsivity of 2200 A W −1 in a vacuum atmosphere for a phototransistor based on monolayer MoS 2 was reported by Zhang et al Meanwhile, under air conditions, the responsivity value decreased to 780 A W −1 because of adsorbates between the surface of MoS 2 and at the MoS 2 /substrate, which act as p‐type dopant materials, arising from recombination and trap centers for photocarriers. In another interesting study, Yore et al fabricated a large‐area (≈1600 µm × 1000 µm) and homogeneous monolayer MoS 2 on a sapphire substrate by CVD methods (Figure b,c), which helped to avoid the effect of photovoltage or photogating arising from the quantum well, which traps either electrons or holes . They employed Ag(contact layer)/Au electrodes, which produce a lower contact resistance.…”

“…The excitation laser wavelength was ≈405 nm. (b, c) Reproduced with permission . Copyright 2017, American Institute of Physics.…”

Recent Advances in van der Waals Heterojunctions Based on Semiconducting Transition Metal Dichalcogenides

“…2018, 4, 1800270 Figure 17. [158,159] This vdWH is expected to be one of the ideal materials for optoelectronic devices in the infrared region. a) Electric circuit schematic of FET devices.…”