Plasmonic enhancement of photocurrent generation in two-dimensional heterostructure of WSe₂/MoS₂

Abstract

Enhancing the photoresponse of single-layered semiconductor materials is a challenge for high-performance photodetectors due to atomically thickness and limited quantum efficiency of these devices. Band engineering in heterostructure of transition metal chalcogenides (TMDs) can sort out part of this challenge. Here, we address this issue by utilizing the plasmonics phenomenon to enrich the optoelectronics property of the WSe2/MoS2 heterojunction and further enhancement of photoresponse. The introduced approach presents a contamination-free, tunable and efficient way to improve light interactions with heterojunction devices. The results showed a 3600-fold enhancement in photoresponsivity and a 46-fold increase in external quantum efficiency (549%) along with a fast photoresponse time (~2 μs) and light polarization dependence. This improvement may assign to multiple light scatterings by the Au nanoarrays and creation of strong local electrical fields (hot spots) at the interfaces of the gold nanoarrays and the TMDs heterostructure. The high-energy electrons (hot electrons) originating from hot spots surmount easily to conduction bands of heterojunction which is leading to a remarkable enhancement of photocurrent. The plasmons assisted photoresponse strategy can be easily matched with the semiconductor industry to boost the performance of optoelectronics devices for practical applications.

WSe2/MoS2 van der Waals Heterostructures Decorated with Au Nanoparticles for Broadband Plasmonic Photodetectors

“…Moreover, we observe that the EQE of our device exceeds 100% in a broadband range of 405–720 nm and falls to 15–62% in the region of 720–1050 nm. Although a similar ultrahigh EQE (150–550%) is also reported by integrating dimer-structured Au NPs with the WSe 2 /MoS 2 heterostructure under an illumination of 395–445 nm, it sharply declines below 100% (470–850 nm) …”

“…Compared with pure TMD-based devices, stacking of them with other 2D materials has a great promotion on the response time. The fabricated vdW heterostructures show an ultrafast response time within microsecond scales, , while the intrinsic TMDs have a slow response time of millisecond even second scales. , After decorating with a metal nanostructure, there is a significant enhancement on the photoresponsivity of devices in both bare 2D materials and their vdW heterostructures. ,− The detection performances of our device herein are not the highest but are already comparable to other plasmonic-enhanced photodetectors with 2D vdW heterostructures, including performance improved by employing LSPR and tunable Fano resonance effects. Moreover, due to the unique distribution of prepared Au NPs and the special band alignment of type-II heterojunction, our fabricated photodetector shows a high responsivity crossing a broadband range from visible to near-infrared wavelengths.…”

“…Although a similar ultrahigh EQE (150−550%) is also reported by integrating dimer-structured Au NPs with the WSe 2 /MoS 2 heterostructure under an illumination of 395−445 nm, it sharply declines below 100% (470−850 nm). 37 The noise equivalent power (NEP) of the device has come from NEP = i N /R, where i N is the noise current spectra within 1 Hz bandwidth and R is the responsivity of the photodetector. For our photodetector, the noise current spectra can be estimated from the dark current with i N = (2eI dark ) 1/2 , where I dark represents the dark current of the photodetector.…”

Enhanced Photoresponse and Wavelength Selectivity by SILAR-Coated Quantum Dots on Two-Dimensional WSe2 Crystals

“…Transition-metal dichalcogenides (TMDs) are emergent materials for photodetection that are broadly studied due to their capability of energy band gap engineering, layered structure, and chemical and physical doping possibilities . Tungsten diselenide (WSe 2 ) is one of the TMDs that is less explored compared to its counterparts, such as WS 2 and MoS 2 .…”

“…8 Transition-metal dichalcogenides (TMDs) are emergent materials for photodetection that are broadly studied due to their capability of energy band gap engineering, layered structure, and chemical and physical doping possibilities. 9 Tungsten diselenide (WSe 2 ) is one of the TMDs that is less explored compared to its counterparts, such as WS 2 and MoS 2 . The WSe 2 flakes have unique properties such as high carrier mobility (250 cm 2 /V s), 10 strong optical absorption (2.13 cm −1 ), 11 large luminescence intensity, 12 and high photoconversion efficiency 13 that make them a potent choice among 2D materials for electronic and optoelectronic applications.…”