A few-layer MoS2 photodetector driven by poly(vinylidene fluoride-trifluoroethylene) ferroelectrics is achieved. The detectivity and responsitivity are up to 2.2 × 10(12) Jones and 2570 A W(-1), respectively, at 635 nm with ZERO gate bias. E(g) of MoS2 is tuned by the ultrahigh electrostatic field from the ferroelectric polarization. The photoresponse wavelengths of the photodetector are extended into the near-infrared (0.85-1.55 μm).
Atomically thin 2D-layered transition-metal dichalcogenides have been studied extensively in recent years because of their intriguing physical properties and promising applications in nanoelectronic devices. Among them, ReSe2 is an emerging material that exhibits a stable distorted 1T phase and strong in-plane anisotropy due to its reduced crystal symmetry. Here, the anisotropic nature of ReSe2 is revealed by Raman spectroscopy under linearly polarized excitations in which different vibration modes exhibit pronounced periodic variations in intensity. Utilizing high-quality ReSe2 nanosheets, top-gate ReSe2 field-effect transistors were built that show an excellent on/off current ratio exceeding 10(7) and a well-developed current saturation in the current-voltage characteristics at room temperature. Importantly, the successful synthesis of ReSe2 directly onto hexagonal boron nitride substrates has effectively improved the electron motility over 500 times and the hole mobility over 100 times at low temperatures. Strikingly, corroborating with our density-functional calculations, the ReSe2-based photodetectors exhibit a polarization-sensitive photoresponsivity due to the intrinsic linear dichroism originated from high in-plane optical anisotropy. With a back-gate voltage, the linear dichroism photodetection can be unambiguously tuned both in the electron and hole regime. The appealing physical properties demonstrated in this study clearly identify ReSe2 as a highly anisotropic 2D material for exotic electronic and optoelectronic applications.
A long-wavelength infrared (IR) photodetector based on two-dimensional materials working at room temperature would have wide applications in many aspects in remote sensing, thermal imaging, biomedical optics, and medical imaging.However, sub-bandgap light detection in graphene and black phosphorus has been a long-standing scientific challenge because of low photoresponsivity, instability in the air and high dark current. In this study, we report a highly sensitive, air-stable and operable long-wavelength infrared photodetector at room temperature based on PdSe2 phototransistors and its heterostructure. A high photoresponsivity of~42.1 AW -1 (at 10.6 μm) was demonstrated, which is an order of magnitude higher than the current 2 record of platinum diselenide. Moreover, the dark current and noise power density were suppressed effectively by fabricating a van der Waals heterostructure. This work fundamentally contributes to establishing long-wavelength infrared detection by PdSe2 at the forefront of long-IR two-dimensional-materials-based photonics.KEYWORDS: photodetector, long-wavelength infrared, photoresponsivity, palladium diselenide, detectivity, heterostructure Scalable two-dimensional, long-wavelength infrared photodetectors operating at room temperature are highly desirable for upcoming remote sensing, thermal imaging, biomedical optics, medical imaging, and space communication applications.State-of-the-art long-wavelength infrared (LWIR) photodetectors based on narrow-bandgap semiconductors using HgCdTe alloy and III-V compound quantum structures suffer from several major challenges, such as the need for operation at liquid nitrogen temperatures, the complexity of sample synthesis and challenging device fabrication processes. 1 Commercial widely used LWIR photodetectors with 5-20 nm wavelength operating at room temperature based on VOx and α-Si possess many advantages such as compatibility with mass production, low price, and facile fabrication processes. However, their low sensitivity, short detection wavelength range and low response speed restrict their application. 2 Recently, the discovery of graphene, a two-dimensional layered material, has offered an opportunity to overcome some of these issues. In previous studies, LWIR photodetectors based on a graphene nanoribbon, 3 graphene quantum dot-like arrays 4 and a graphene heterostructure 5 have been demonstrated. Generally, the photoresponsivity has been low, approximately 7.5 μA W -1 in the graphene nanoribbon, due to the limited light absorption of 2.3% in an atomic thin layer, 6 and a high dark current due to the gapless band structure. Although strategies such as surface plasma enhanced light absorption 7 and carrier multiplication [8][9][10] have been adopted to enhance the photoresponsivity of graphene photodetectors, the photoresponsivity is still relatively low at several tens of mA W -1 .A photoresponsivity of up to 0.4 AW -1 at 10.6 μm was demonstrated by etching graphene to form quantum-dot-like arrays. 4 The resulting high responsivity was 16 ...
An advanced visible/infrared dual-band photodetector with high-resolution imaging at room temperature is proposed and demonstrated for intelligent identification based on the 2D GaSe/GaSb vertical heterostructure. It resolves the challenges of producing large-scale 2D growth, achieving fast response speed, outstanding detectivity, and lower manufacture cost, which are the main obstacles for industrialization of 2D-materials-based photodetection.
Blackbody-sensitive room-temperature infrared detection is a notable development direction for future low-dimensional infrared photodetectors. However, because of the limitations of responsivity and spectral response range for low-dimensional narrow bandgap semiconductors, few low-dimensional infrared photodetectors exhibit blackbody sensitivity. Here, highly crystalline tellurium (Te) nanowires and two-dimensional nanosheets were synthesized by using chemical vapor deposition. The low-dimensional Te shows high hole mobility and broadband detection. The blackbody-sensitive infrared detection of Te devices was demonstrated. A high responsivity of 6650 A W−1 (at 1550-nm laser) and the blackbody responsivity of 5.19 A W−1 were achieved. High-resolution imaging based on Te photodetectors was successfully obtained. All the results suggest that the chemical vapor deposition–grown low-dimensional Te is one of the competitive candidates for sensitive focal-plane-array infrared photodetectors at room temperature.
2D layered materials are an emerging class of low-dimensional materials with unique physical and structural properties and extensive applications from novel nanoelectronics to multifunctional optoelectronics. However, the widely investigated 2D materials are strongly limited in high-performance electronics and ultrabroadband photodetectors by their intrinsic weaknesses. Exploring the new and narrow bandgap 2D materials is very imminent and fundamental. A narrow-bandgap noble metal dichalcogenide (PtS 2 ) is demonstrated in this study. The few-layer PtS 2 field-effect transistor exhibits excellent electronic mobility exceeding 62.5 cm 2 V −1 s −1 and ultrahigh on/off ratio over 10 6 at room temperature. The temperature-dependent conductance and mobility of few-layer PtS 2 transistors show a direct metal-to-insulator transition and carrier scattering mechanisms, respectively. Remarkably, 2D PtS 2 photo detectors with broadband photodetection from visible to mid-infrared and a fast photoresponse time of 175 µs at 830 nm illumination for the first time are obtained at room temperature. Our work opens an avenue for 2D noble-metal dichalcogenides to be applied in high-performance electronic and mid-infrared optoelectronic devices.
Low‐symmetry 2D materials with unique anisotropic optical and optoelectronic characteristics have attracted a lot of interest in fundamental research and manufacturing of novel optoelectronic devices. Exploring new and low‐symmetry narrow‐bandgap 2D materials will be rewarding for the development of nanoelectronics and nano‐optoelectronics. Herein, sulfide niobium (NbS3), a novel transition metal trichalcogenide semiconductor with low‐symmetry structure, is introduced into a narrowband 2D material with strong anisotropic physical properties both experimentally and theoretically. The indirect bandgap of NbS3 with highly anisotropic band structures slowly decreases from 0.42 eV (monolayer) to 0.26 eV (bulk). Moreover, NbS3 Schottky photodetectors have excellent photoelectric performance, which enables fast photoresponse (11.6 µs), low specific noise current (4.6 × 10−25 A2 Hz−1), photoelectrical dichroic ratio (1.84) and high‐quality reflective polarization imaging (637 nm and 830 nm). A room‐temperature specific detectivity exceeding 107 Jones can be obtained at the wavelength of 3 µm. These excellent unique characteristics will make low‐symmetry narrow‐bandgap 2D materials become highly competitive candidates for future anisotropic optical investigations and mid‐infrared optoelectronic applications.
One-dimensional InAs nanowire (NW)-based photodetectors have been widely studied due to their potential application in mid-wavelength infrared (MWIR) photon detection. However, the limited performance and complicated photoresponse mechanism of InAs NW-based photodetectors have held back their true potential for real application. In this study, we developed ferroelectric polymer P(VDF-TrFE)-coated InAs NW-based photodetectors and demonstrated that the electrostatic field caused by polarized ferroelectric materials modifies the surface electron–hole distribution as well as the band structure of InAs NWs, resulting in ultrasensitive photoresponse and a wide photodetection spectral range. Our single InAs NW photodetectors exhibit a high responsivity (R) of 1.6 × 104 A W–1 as well as a corresponding detectivity (D*) of 1.4 × 1012 cm·Hz1/2 W–1 at a light wavelength of 3.5 μm without an applied gate voltage, ∼3–4 orders higher than the maximum value of photoresponsivity reported or commercially used MWIR photodetectors. Moreover, our device shows below band gap photoresponse for 4.3 μm MWIR light with R of 9.6 × 102 A W–1 as well as a corresponding D* of ∼8.5 × 1010 cm·Hz1/2 W–1 at 77 K. Our study shows that this approach is promising for fabrication of high-performance NW-based photodetectors for MWIR photon detection.
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