One dimensional (1D)-two dimensional (2D) van der Waals (vdWs) mixed-dimensional heterostructures with advantages of atomically sharp interface, high quality and good compatibility have attracted tremendous attention in recent years. The...

The widespread application of photodetectors has triggered an urgent need for high-sensitivity and polarization-dependent photodetection. In this field, the two-dimensional (2D) tungsten disulfide (WS 2 ) exhibits intriguing optical and electronic properties, making it an attractive photosensitive material for optoelectronic applications. However, the lack of an effective built-in electric field and photoconductive gain mechanism in 2D WS 2 impedes its application in high-performance photodetectors. Herein, we propose a hybrid heterostructure photodetector that contains 1D Te and 2D WS 2 . In this device, 1D Te induces in-plane strain in 2D WS 2 , which regulates the electronic structures of local WS 2 and gives rise to type-II band alignment in the horizontal direction. Moreover, the vertical heterojunction built of 2D WS 2 and 1D Te introduces a high photoconductive gain. Benefiting from these two effects, the transfer of photogenerated carriers is optimized, and the proposed photodetector exhibits high sensitivity (photoresponsivity of ~27.7 A W −1 , detectivity of 9.5 × 10 12 Jones, and short rise/ decay time of 19.3/17.6 ms). In addition, anisotropic photodetection characteristics with a dichroic ratio up to 2.1 are achieved. This hybrid 1D/2D heterostructure overcomes the inherent limitations of each material and realizes novel properties, opening up a new avenue towards constructing multifunctional optoelectronic devices.

Monoelemental two-dimensional (2D) Tellurium (Te) has demonstrated excellent potential candidate for next-generation (opto)electronic devices due to its unique properties such as topological surface states, high carrier mobility, high light absorption...

Bi 2 O 2 Se nanosheets, an emerging ternary non-van der Waals two-dimensional (2D) material, have garnered considerable research attention in recent years owing to their robust air stability, narrow indirect bandgap, high mobility, and diverse intriguing properties. However, most of them show high dark current and relatively low light on/off ratio and slow response speed because of the large charge carrier concentration and bolometric effect, hindering their further application in low-energy-consuming optoelectronics. Herein, a homotype van der Waals heterostructure based on exfoliated n-InSe integrated with chemical vapor deposition (CVD)grown n-Bi 2 O 2 Se nanosheets that have type II band alignment was fabricated. The efficient interfacial charge separation, strong interlayer coupling, and effective built-in electric field across the heterointerface demonstrated excellent, stable, and broadband self-driven photodetection in the range 400−1064 nm. Specifically, a high responsivity (R) of 75.2 mA•W −1 and a high specific detectivity (D*) of 1.08 × 10 12 jones were achieved under 405 nm illumination. Additionally, a high R of 13.3 mA•W −1 and a high D* of 2.06 × 10 11 jones were achieved under 980 nm illumination. Meanwhile, an ultrahigh I light /I dark ratio over 10 5 and a fast response time of 5.8/15 ms under 405 nm illumination confirmed the excellent photosensitivity and fast response behavior. Furthermore, R could be enhanced to 13.6 and 791 mA•W −1 under 405 and 980 nm illumination at a drain−source voltage (V ds ) of 1 V, respectively, originating from a lower potential barrier. This study suggested that the Bi 2 O 2 Se nanosheet/InSe nanoflake homotype heterojunction can offer potential applications in next-generation broadband photodetectors that consume low energy and exhibit high performance.

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In recent years, polarization-sensitive photodiodes based on one-dimensional/two-dimensional (1D/2D) van der Waals (vdWs) heterostructures have garnered significant attention due to the high specific surface area, strong orientation degree of 1D structures, and large photo-active area and mechanical flexibility of 2D structures. Therefore, they are applicable in wearable electronics, electrical-driven lasers, image sensing, optical communication, optical switches, etc. Herein, 1D Bi2O2Se nanowires have been successfully synthesized via chemical vapor deposition. Impressively, the strongest Raman vibration modes can be achieved along the short edge (y-axis) of Bi2O2Se nanowires with high crystalline quality, which originate from Se and Bi vacancies. Moreover, the Bi2O2Se/MoSe2 photodiode designed with type-II band alignment demonstrates a high rectification ratio of 103. Intuitively, the photocurrent peaks are mainly distributed in the overlapped region under the self-powered mode and reverse bias, within the wavelength range of 400–nm. The resulting device exhibits excellent optoelectrical performances, including high responsivities (R) and fast response speed of 656 mA/W and 350/380 μs (zero bias) and 17.17 A/W and 100/110 μs (−1 V) under 635 nm illumination, surpassing the majority of reported mixed-dimensional photodiodes. The most significant feature of our photodiode is its highest photocurrent anisotropic ratio of ∼2.2 (−0.8 V) along the long side (x-axis) of Bi2O2Se nanowires under 635 nm illumination. The above results reveal a robust and distinctive correlation between structural defects and polarized orientation for 1D Bi2O2Se nanowires. Furthermore, 1D Bi2O2Se nanowires appear to be a great potential candidate for high-performance rectifiers, polarization-sensitive photodiodes, and phototransistors based on mixed vdWs heterostructures.

Carrier mobility is one of most important figures of merit for materials that can determine to a large extent the corresponding device performances. So far, extensive efforts have been devoted to the mobility improvement of two-dimensional (2D) materials regarded as promising candidates to complement the conventional semiconductors. Graphene has amazing mobility but suffers from zero bandgap. Subsequently, 2D transition-metal dichalcogenides benefit from their sizable bandgap while the mobility is limited. Recently, the 2D elemental materials such as the representative black phosphorus can combine the high mobility with moderate bandgap; however the air-stability is a challenge. Here, we report air-stable tellurium flakes and wires using the facile and scalable physical vapour deposition (PVD) method. The prototype field-effect transistors were fabricated to exhibit high hole mobility up to 1485 cm 2 V −1 s −1 at room temperature and 3500 cm 2 V −1 s −1 at low temperature (2 K). This work can attract numerous attentions on this new emerging 2D tellurium and open up a new way for exploring high-performance optoelectronics based on the PVD-grown p-type tellurium.

In this work, a p-n junction-coupled metal-insulator-semiconductor (MIS) normally-off high-electron-mobility transistor (HEMT) UVPD is proposed. A two-dimensional electron gas (2DEG) at the AlN/U-GaN interface is entirely depleted with a dark current of 1.97 × 10−11 A because of the design of the sandwiched p-GaN layers. Under 365 nm illumination, the 2DEG is light triggered at Vds = 1 V with a high light on/off ratio of over 107 at a light power density of 286.39 mW·cm−2. Meanwhile, it exhibits fast rise and decay times of 248.39 and 584.79 µs, respectively. Moreover, a maximum responsivity (R) of 2.33 A/W, a maximum EQE of 793%, and a D* of 1.08 × 1013 Jones are obtained at Vds = 1 V. This can be attributed to the built-in electric fields in the configuration, which accelerate the flow of photogenerated carriers into the AlN/U-GaN channel. Additionally, the device showcases stable durability, repeatability, and a low driving voltage, making it highly suitable for applications in UV communication and space exploration.