Responsivity

About: Responsivity is a research topic. Over the lifetime, 9918 publications have been published within this topic receiving 186118 citations.

Plasmonically enhanced graphene photodetector featuring 100 GBd, high-responsivity and compact size

Abstract: Graphene has shown great potentials for high-speed photodetection. Yet, the responsivities of graphene-based high-speed photodetectors are commonly limited by the weak effective absorption of atomically thin graphene. Here, we propose and experimentally demonstrate a plasmonically enhanced waveguide-integrated graphene photodetector. The device which combines a 6 micron long layer of graphene with field-enhancing nano-sized metallic structures, demonstrates a high external responsivity of 0.5 A/W and a fast photoresponse way beyond 110 GHz. The high efficiency and fast response of the device enables for the first time 100 Gbit/s PAM-2 and 100 Gbit/s PAM-4 data reception with a graphene based device. The results show the potential of graphene as a new technology for highest-speed communication applications.

Layered ultrathin PbI2 single crystals for high sensitivity flexible photodetectors

Abstract: A facile and novel method has been developed to prepare ultrathin PbI2 single crystals with good mechanical flexibility and bendability for high sensitivity photodetectors. The prototype lateral metal–semiconductor–metal photodetector based on the as-prepared crystal exhibits a responsivity of up to 11.3 A W−1, a photogain of 31.84, and a high-speed photoresponse with a time constant of 354 μs.

Charge-integrating organic heterojunction phototransistors for wide-dynamic-range image sensors

Abstract: Solution-processed phototransistors can substantially advance the performance of image sensors. Phototransistors exhibit large photoconductive gain and a sublinear responsivity to irradiance, which enables a logarithmic sensing of irradiance that is akin to the human eye and has a wider dynamic range than photodiode-based image sensors. Here, we present a novel solution-processed phototransistor composed of a heterostructure between a high-mobility organic semiconductor and an organic bulk heterojunction. The device efficiently integrates photogenerated charge during the period of a video frame then quickly discharges it, which significantly increases the signal-to-noise ratio compared with sampling photocurrent during readout. Phototransistor-based image sensors processed without photolithography on plastic substrates integrate charge with external quantum efficiencies above 100% at 100 frames per second. In addition, the sublinear responsivity to irradiance of these devices enables a wide dynamic range of 103 dB at 30 frames per second, which is competitive with state-of-the-art image sensors. A solution-processed organic phototransistor is operated at 100-frame-per-second rates with external quantum efficiencies above 100%. Dynamic range as high as 103 dB was shown for 30-frame-per-second operation.

Quantum efficiency enhancement of AlGaAs/GaAs quantum well infrared detectors using a waveguide with a grating coupler

Abstract: Long wavelength quantum well detectors with very high quantum efficiency, based on the coupling of radiation into an optical resonant cavity or waveguide defined by a reflection grating coupler on one side of the infrared absorbing multiquantum well stack, and an aluminum arsenide cladding layer on the other, have been fabricated and the results compared with theory. Theory shows that quantum efficiencies up to 90% may be obtained (for polarized radiation). However, experimental results indicate that the response peak becomes broadened due to spread in the grating period and therefore the maximum quantum efficiency is in practice limited to 60%, corresponding to a current responsivity of 2.1 A/W. This is 2.7 times larger than for a 45° polished edge detector with the same quantum well characteristics.

High-efficiency and air-stable photodetectors based on lead-free double perovskite Cs2AgBiBr6 thin films

Abstract: Halide perovskite-based photodetectors, because of their fundamental scientific importance and practical applications in the military and civil fields, have drawn worldwide attention in recent years. However, the toxicity and instability issues are major challenges for their mass production and commercialization. In this study, for the first time, we report the use of the one-step spin-coating method for the preparation of lead-free double perovskite Cs2AgBiBr6 thin films for photodetector applications. The morphology, crystallinity, and optical properties of the as-grown Cs2AgBiBr6 thin films were first investigated. Further, symmetrically structured photoconductive detectors were fabricated and characterized. The device performance was remarkable in terms of a high responsivity of 7.01 A W−1, an on/off photocurrent ratio of 2.16 × 104, a specific detectivity of 5.66 × 1011 Jones, an external quantum efficiency of 2146%, and a fast response speed of 956/995 μs. More importantly, the unencapsulated photodetectors demonstrate remarkable operational stability over the aging test (36 h, 35–45% humidity), and the photodetection ability can be almost maintained. Moreover, after storage for two weeks in ambient air, the proposed photodetectors can be efficiently sustained, demonstrating remarkable stability against water and oxygen degradation. Our results indicate that lead-free double perovskite Cs2AgBiBr6 is potentially an environmentally friendly alternative to fabricate high-efficiency and stable perovskite photodetectors for practical applications.