Rational Design of WSe₂/WS₂/WSe₂ Dual Junction Phototransistor Incorporating High Responsivity and Detectivity

Abstract

The excellent semiconducting properties and ultrathin morphological characteristics allow van der Waals (vdW) heterostructures based on 2D materials to be promising channel materials for the next‐generation optoelectronic devices, especially in photodetectors. Although various 2D heterostructure‐based photodetectors have been developed, the unavoidable trade‐off between responsivity and detectivity remains a critical issue for these devices. Here, an ingenious phototransistor based on WSe2/WS2/WSe2 dual‐vdW heterostructures is constructed, performing both high responsivity and detectivity. In the charge neutrality point (gate voltage of −15 V and bias voltage of 1 V), this device demonstrates a pronounced photosensitivity, accompanying with high detectivity of 1.9 × 1014 Jones, high responsivity of 35.4 A W−1, and fast rise/fall time of 3.2/2.5 ms at 405 nm with power density of 60 µW cm−2. Density functional theory calculations, energy band profiles, and optoelectronic characteristics jointly verify that the high performance is ascribed to the distinctive device design, which not only facilitates the separation of photogenerated carriers but also produces a strong photogating effect. As a feasible application, an automotive radar system is demonstrated, proving that the device has considerable potential for application in vehicle intelligent assisted driving.

High‐Performance and Polarization‐Sensitive Imaging Photodetector Based on WS2/Te Tunneling Heterostructure

“…[15][16][17][18][19] Consequent 2D vdW heterostructures with engineered band alignment exhibit unique properties beyond individual components. [15,18,20] Therefore, 2D vdW heterostructures are promising for developing next-generation imaging photodetectors.To date, a variety of 2D vdW heterostructures aiming at photodetectors have been constructed, such as WSe 2 /Bi 2 O 2 Se, [21]…”

“…[15][16][17][18][19] Consequent 2D vdW heterostructures with engineered band alignment exhibit unique properties beyond individual components. [15,18,20] Therefore, 2D vdW heterostructures are promising for developing next-generation imaging photodetectors.…”

Self-Powered Photodetector with High Efficiency and Polarization Sensitivity Enabled by WSe2/Ta2NiSe5/WSe2 van der Waals Dual Heterojunction

“…A strong PL emission signal around 890 nm and a weak shoulder peak at 780 nm for bare WSe 2 can be clearly observed, which correspond to the recombination of indirect transition I peak and A exciton peak, respectively . Significantly, the PL peak for the overlapped DHJ region without shift undergoes quenching in consequence of the efficient separation and transition of photogenerated carriers across the heterostructures. , …”

“…Furthermore, the wavelength-dependent normalized photocurrent of DHJ devices was measured, as depicted in Figure c. It is observed that there are two photoresponse peaks at 650 and 760 nm in the DHJ device, which is close to the indirect transition A excitation peak of WSe 2 , thus indicating that the top and bottom WSe 2 layers mainly contribute to the spectral response.…”

Ultra-high photo responsivity and self-powered photodetector in broad spectral range based on non-layered MnSe/WSe2 heterojunction

“…The field-effect transistors (FETs) with a small number of layers of WSe 2 achieved a carrier mobility of up to 70.1 cm 2 V −1 s −1 and open-light ratio of over 10 6 , using Al 2 O 3 as the top gate (Liu et al, 2013). Therefore, heterojunctions formed by stacking WSe 2 and other 2D materials will help to improve the electronic and optoelectronic performance (Feng et al, 2022;Luo et al, 2022).…”