Terahertz (THz) photon detection is of particular appealing for myriad applications, but it still lags behind efficient manipulation with electronics and photonics due to the lack of a suitable principle satisfying both high sensitivity and fast response at room temperature. Here, a new strategy is proposed to overcome these limitations by exploring the photothermoelectric (PTE) effect in an ultrashort (down to 30 nm) channel with black phosphorus as a photoactive material. The preferential flow of hot carriers is enabled by the asymmetric Cr/Au and Ti/Au metallization with the titled‐angle evaporation technique. Most intriguingly, orders of magnitude field‐enhancement beyond the skin‐depth limit and photon absorption across a broadband frequency can be achieved. The PTE detector has excellent sensitivity of 297 V W−1, noise equivalent power less than 58 pW/Hz0.5, and response time below 0.8 ms, which is superior to other thermal‐based detectors at room temperature. A rigorous comparison with existing THz detectors, together with verification by further optical‐pumping and imaging experiments, substantiates the importance of the localized field effect in the skin‐depth limit. The results allow solid understanding on the role of PTE effect played in the THz photoresponse, opening up new opportunities for developing highly sensitive THz detectors for addressing targeted applications.

The noble transition metal dichalcogenide palladium diselenide (PdSe2) is an ideal candidate material for broad-spectrum photodetection owing to the large bandgap tunability, high mobility, low thermal conductivity, and large Seebeck coefficient. In this study, self-powered ultrabroadband PdSe2 photodetectors from the visible–infrared to terahertz (THz) region driven by a mutiphysical mechanism are reported. In the visible–infrared region, the photogenerated electron–hole pairs in the PdSe2 body are quickly separated by the built-in electric field at the metal–semiconductor interface and achieve a photoresponsivity of 28 A·W–1 at 405 nm and 0.4 A·W–1 at 1850 nm. In the THz region, PdSe2 photodetectors display a room-temperature responsivity of 20 mA·W–1 at 0.10 THz and 5 mA·W–1 at 0.24 THz based on efficient production of hot carriers in an antenna-assisted structure. Owing to the fast response speed of ∼7.5 μs and low noise equivalent power of ∼900 pW·Hz–1/2, high-resolution transmission THz imaging is demonstrated under an ambient environment at room temperature. Our research validates the great potential of PdSe2 for broadband photodetection and provides a possibility for future optoelectronic applications.

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Two-dimensional (2D) inorganic/organic heterostructures have attracted great attention in the field of optoelectronics due to their unique properties. Comparing with purity organic semiconductors or 2D inorganic heterostructures, the 2D inorganic/organic heterostructure overwhelms the current limitations of photodetectors and provides more opportunities for the optoelectronic field. However, no in-depth reviews on the important progresses, challenges, and optimizing strategies of performance of photodetectors based on 2D inorganic/organic heterostructures are found in literatures to date. Herein, this report firstly introduces unique features of 2D inorganic/organic heterostructures. Then, we sum up the main growing methods according to the technological principle, and the main properties of photodetectors, and summarize the progresses of photodetectors of 2D inorganic-organic heterostructures based on different physical mechanisms (mainly as photovoltaic effect and photoconductive effect). More importantly, this report presents some design strategies for optimizing photodetector performance of 2D inorganic-organic heterostructures, especially introducing 2D organic ultrathin film design strategy. Furthermore, future challenges and opportunities of 2D inorganic-organic heterostructures are highlighted.

and weak charge storage capability with the size reduction. [4][5][6][7] To this end, ferroelectric random access memory (FeRAM) becomes one of the growing number of alternative technologies, which shows great advantages referring to the faster write performance and much greater maximum read/write endurance. [8,9] Traditional FeRAM is in a single capacitance structure, composed of ferroelectric (FE) materials with spontaneous polarization and top/bottom electrodes. It achieves two stable nonvolatile states as "0" and "1" to implement information storage with the application of electric fields. [10][11][12][13] Despite the great promise it holds, the commercial prospect of FeRAM is hampered by virtue of low integration. In particular, the read operation of FeRAM is destructive and reprogramming is needed after each readout process, resulting in high power consumption and prolonged readout time. [13,14] While, the drawbacks of a single capacitor-type FeRAM can be ameliorative if the device structure replaced by field effect transistor (FET), which benefits from its nondestructive readout operation and excellent compatibility with the current complementary metal-oxide-semiconductor technology. [15][16][17][18] By this means, the FE materials, served as gate insulator, are combined with semiconductors to form a synergistic heterostructure system with novel functionalities.Relative to conventional semiconductors, 2D ones, such as transition metal dichalcogenides (TMDs) [19] and black phosphorus (BP), [20,21] are more suitable to construct of synergistic heterostructure devices. On one hand, 2D materials enable versatile heterostructure integration with other 1D, 2D, and 3D counterparts through van de Waals coupling. More significantly, atomically thin characteristic of 2D materials is prone to high integration density and provides convenience for gating tunability. Lead zirconate titanate (PZT)-gated few-layer graphene have been previously reported to process an extremely high mobility of µ ∼ 7 × 10 4 cm 2 V −1 s −1 . [22] It has been also reported that FE material as gating dielectric can tune the transport behavior and improve electrical performance of the 2D FETs. [23][24][25][26] Thereby, the combination of 2D semiconductors and FE materials has potential to provide an excellent platform Ferroelectric-field-effect-transistor (FeFET) memory, characterized by its nonvolatile, nondestructive readout operation and low power consumption, has attracted tremendous attention in the development of next-generation random-access memory. However, the electrical reading processes in conventional FeFETs may attenuate the ferroelectric (FE) polarization and lead to readout crosstalk. A photoelectric-type FeFET memory with alternative readout through 2D black phosphorus (BP)/lead zirconate titanate (PZT) heterostructures is developed. Based on charge-mediated electric-field control, a unique polarization-dependent photoresponse is observed, resulting in both positive photoconductivity (PPC) and negative photoconductivity (NPC) in...

Highlights High-quality 2D Te nanoflakes were directly synthesized by CVT method The growth mechanisms of 2D Te nanoflakes were systematically studied 2D Te nanoflakes have potential applications in nonlinear optical devices 2D Te nanoflakes-based FETs exhibit high mobility of $379 cm 2 V À1 s À1

Dual-band photodetectors have attracted intensive attention because of the requirement of multiband information [such as visible (VIS) and near-infrared (NIR)] in multicolor imaging technology, in which additional information beyond human vision could assist object identification and navigations. The use of 2D materials can break the limitation of high cost of conventional epitaxial semiconductors and a complex cryogenic cooling system for multi-band detection, but there is still much room to improve the performance, especially in responsivity and signal noise ratio. Herein, we have fabricated a VIS-NIR dual-band photodetector based on a multilayer Ta2NiSe5/GaSe heterojunction. Benefiting from the type-II heterojunction, the separation of photo-induced carriers is naturally enhanced, which promotes the responsivity of this dual-band photodetector to 4.8 A W−1 (VIS) and 0.15 A W−1 (NIR) at room temperature with a suppressed dark current at ∼4 pA. Our work suggests that the Ta2NiSe5/GaSe heterostructure is a promising candidate for ultrasensitive VIS-NIR dual-band photodetection.