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- 实验方案
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High-responsivity Two-dimensional p-PbI <sub/>2</sub> /n-WS <sub/>2</sub> Vertical Heterostructure Photodetectors Enhanced by Photogating Effect
摘要： Two-dimensional (2D) vertical p-n heterostructure photodetectors are significant building blocks in nanoscale integrated optoelectronics. However, the unsatisfactory photosensing performance combined with complicated fabrication process still remains a challenge. In this work, the fabrication of high performance vertical photodetectors based on vapor grown p-PbI2/n-WS2 heterostructures is reported, in which the WS2 serves as the photogate to modulate the channel current. Due to the photogating effect in the heterostructures, the recombination of photo-excited electron–hole pairs is effectively suppressed, leading to high photoresponsivity up to 5.57 × 102 A W-1, which represents the highest value among the ever reported vapor-grown vertical p-n heterostructures. Moreover, the photoresponsivity is highly tunable through the gate voltage bias, and can be further improved to 7.1 × 104 A W-1 by applying a negative gate voltage bias of -60 V. The excellent photosensing properties of the PbI2/WS2 heterostructures combined with the facile synthesis method suggest a great potential in developing high performance 2D optoelectronic devices.
关键词： vertical p-n heterostructure,photogating effect,vapor deposition,photodetectors,Two-dimensional
更新于2025-11-14 17:04:02
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Color Sensitive Response of Graphene / Graphene Quantum Dot Phototransistors
摘要： We present the fabrication and characterization of all-carbon phototransistors made of graphene three terminal devices coated with atomically precise graphene quantum dots (GQD). Chemically synthesized GQDs are the light absorbing materials, while the underlying chemical vapor deposition (CVD)-grown graphene layer acts as the charge transporting channel. We investigated three types of GQDs with different sizes and edge structures, having distinct and characteristic optical absorption in the UV-Vis range. The photoresponsivity exceeds 106 A/W for vanishingly small incident power (<10-12 W), comparing well with state of the art sensitized graphene photodetectors. More importantly, the photoresponse is determined by the specific absorption spectrum of each GQD, exhibiting the maximal responsivity at the wavelengths corresponding to the absorption maxima. Overall this behavior can be ascribed to the efficient and selective absorption of light by the GQDs, followed by a charge transfer to graphene, a mechanism known as photogating effect. Our results suggest the use of graphene/GQD devices as valuable photodetectors for application where color sensitivity is required.
关键词： graphene,graphene quantum dots,phototransistors,color sensitivity,photogating effect
更新于2025-09-19 17:13:59
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Asymmetric Contact Induced Self-Powered 2D In2S3 Photodetector towards High-Sensitivity and Fast-Response
摘要： Self-powered photodetectors have triggered extensive attention in recent years due to the advantages of high sensitivity, fast response, low power consumption, high level of integration and wireless operation. To date, most self-powered photodetectors are implemented through the construction of either heterostructures or asymmetric electrode material contact, which are complex to process and costly to produce. Herein, for the first time, we achieve self-powered operation by adopting geometrical asymmetry in the device architecture, where a triangular non-layered 2D In2S3 flake with asymmetric contact is combined with traditional photogating effect. Importantly, the device achieves excellent photoresponsivity (740 mA/W), high detectivity (1.56 × 1010 Jones), and fast response time (9/10 ms) under zero bias. Furthermore, the asymmetric In2S3/Si photodetector manifests long-term stability. Even after 1000 cycles of operation, the asymmetric In2S3/Si device displays negligible performance degradation. In sum, the above results highlight a novel route towards self-powered photodetectors with high performance, simple processing and structure in the future.
关键词： high sensitivity,fast response,asymmetric contact,Self-powered photodetectors,2D In2S3,photogating effect
更新于2025-09-19 17:13:59
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High-specific-detectivity, low-dark-current Ge nanowire metal-semiconductor-metal photodetectors fabricated by Ge condensation method
摘要： We have investigated Ge nanowire (NW) metal-semiconductor-metal (MSM) photodetectors with high specific detectivity and low dark current, in which various sizes Ge NWs were fabricated by three-dimensional (3D) Ge condensation techniques. It has been demonstrated that the photocurrent gain increases significantly from 6.31×104 to 4.47×106 with the reduction of Ge NW width from 170 to 35 nm. A low dark current of 5.1 nA and an ultra-high specific detectivity of 1.26×1014 cm·Hz1/2·W-1 at 560 nm under 0.51 V bias are achieved for the 35 nm wide Ge NW photodetector. It has been proposed that the interface states provided by SiGeOx formed during Ge condensation process serve as electron traps to generate photogating effect, resulting in high photocurrent gain and high specific detectivity in the MSM photodetector. The fully complementary metal-oxide-semiconductor (CMOS) compatible and scalable process suggests a great potential of the Ge NW for low cost, high performance near infrared photodetectors.
关键词： gain,Ge nanowire photodetector,Ge condensation technique,photogating effect
更新于2025-09-12 10:27:22
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Enhanced NO2 gas sensing of a single-layer MoS2 by photogating and piezo-phototronic effects
摘要： NO2 sensors with ultrahigh sensitivity are demanded for future electronic sensing systems. However, traditional sensors are considerably limited by the relative low sensitivity, high cost and complicated process. Here, we report a simply and reliable flexible NO2 sensor based on single-layer MoS2. The flexible sensor exhibits high sensitivity to NO2 gas due to ultra-large specific surface area and the nature of two-dimensional (2D) semiconductor. When the NO2 is 400 ppb (parts per billion), compared with the dark and strain-free conditions, the sensitivity of the single-layer sensor is enhanced to 671% with a 625 nm red light-emitting diode (LED) illumination of 4 mW/cm2 power under 0.67% tensile strain. More important, the response time is dramatically reduced to ～16 s and it only needs ～65 s to complete 90% recovery. A theoretical model is proposed to discuss the microscopic mechanisms. We find that the remarkable sensing characteristics are the result of coupling among piezoelectricity, photoeletricity and adsorption-desorption induced charges transfer in the single-layer MoS2 Schottky junction based device. Our work opens up the way to further enhancements in the sensitivity of gas sensor based on single-layer MoS2 by introducing photogating and piezo-phototronic effects in mesoscopic systems.
关键词： photogating effect,single-layer MoS2,ultrahigh sensitivity,flexible NO2 sensor,piezo-phototronic effect
更新于2025-09-04 15:30:14