Abstract
One-dimensional (1D)–two-dimensional (2D) van der Waals (vdWs) mixed-dimensional heterostructures with advantages of an atomically sharp interface, high quality and good compatibility have attracted tremendous attention in recent years. Herein, a mixed-dimensional vertical heterostructure is constructed by transferring mechanically exfoliated 2D WS2 nanosheets on epitaxially grown 1D tellurium (Te) microwires. According to the theoretical type-II band alignment, the device exhibits a photovoltaic effect and serves as an excellent self-powered photodetector with a maximum open-circuit voltage (Voc) up to ∼0.2 V. Upon 635 nm light illumination, the photoresponsivity, external quantum efficiency and detectivity of the self-powered photodetector (SPPD) are calculated to be 471 mA W−1, 91% and 1.24 × 1012 Jones, respectively. Moreover, the dark current of the SPPD is highly suppressed to the sub-pA level due to the large lateral built-in electric field, which leads to a high Ilight/Idark ratio of 104 with a rise time of 25 ms and decay time of 14.7 ms. The abovementioned properties can be further enhanced under a negative bias of −2 V. In brief, the 1D Te–2D WS2 mixed-dimensional heterostructures have great application potential in high performance photodetectors and photovoltaics.
Highlights
The dark current of the self-powered photodetector (SPPD) is highly suppressed to the sub-pA level due to the large lateral built-in electric field, which leads to a high Ilight/Idark ratio of 104 with a rise time of 25 ms and decay time of 14.7 ms
We demonstrate a mixed-dimensional heterostructure of 1D Te microwires covered by 2D WS2 nanosheets via a polyvinyl alcohol (PVA) dry transfer method
A mixed-dimensional heterostructure based on the 1D Te microwire and 2D WS2 nanosheet has been fabricated for high performance photodetectors
Summary
Due to the quantum con nement effect and the strong interlayer coupling effect, two-dimensional (2D) layered materials such as transition metal dichalcogenides (TMDs) (molybdenum disul de, tungsten disul de, etc.) have attracted tremendous attention with unique thickness dependent and strain-tunable physical properties.[1,2,3,4,5,6,7] In recent years, beyond the discovery of graphene, other novel monoelemental 2D layered materials such as black phosphorus (BP), arsenic (As), bismuth (Bi), tellurium (Te), and antimonene (Sb), which show a tunable band gap, high theoretical carrier mobility, atomically at surface, strong spin orbital torque, and high light absorption efficiency, have been experimentally explored as promising candidates for applications in eld effect transistors (FETs),(vdWs) forces along the c-axis, leading to the mixed formation type of wires and nanosheets.[12]. The fabricated Te–WS2 heterostructure theoretically has a type-II (staggered gap) band arrangement attributing to the PL quenching effect, which can facilitate the photo-generated carrier generation and separation at the heterointerface.[46] A er contact, the band alignment becomes bent and the electrons and holes can transfer within interlayers via a built-in electric eld pointing from n-WS2 to the p-Te microwire.[47]
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