Responsivity

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

Characteristics of InGaAs quantum dot infrared photodetectors

Abstract: A quantum dot infrared photodetector (QDIP) consisting of self-assembled InGaAs quantum dots has been demonstrated Responsivity of 325 mA/W at 92 μm was obtained for nonpolarized incident light on the detector with a 45° angle facet at 60 K The QDIPs exhibit some unique electro-optic characteristics such as a strong negative differential photoconductance effect and blueshift of the response peak wavelength

A review of photodetectors for sensing light-emitting reporters in biological systems

Abstract: A review of photodetectors for optical detection in biological applications is presented. The intent is to provide an overview of the performance metrics and trade-offs among popular photodetectors in order to facilitate an easier match among the photodetector, biological stimulus, and optical pathway. The characteristics and nonidealities of fluorescent and phosphorescent reporters, and the properties of optical components such as filters, lenses, and light sources, are reviewed. By accounting for sources of noise in these components, it is shown how to determine metrics for the optical system that can then be converted to photodetector metrics. Defined photodetector metrics include the quantum efficiency, responsivity, noise-equivalent power, detectivity, gain, dark current, response time, and noise spectrum. The operating principles and performance trade-offs of photodetectors are reviewed, and emphasis is placed on photodetectors for integrated compact systems. Top commercial candidates for photodetectors for detecting light emitted from reporters are the photomultiplier tube, avalanche photodiode, and charge-coupled device. Focus is placed on new developments in complementary metal-oxide-semiconductor structures that can provide low-cost, low-power, and low-voltage alternatives to traditional approaches to biological imaging. Reviewed device structures are presented in the context of supporting the development of laboratory-based instruments and compact fully-integrated systems.

Ultrabroadband and High-Detectivity Photodetector Based on WS2/Ge Heterojunction through Defect Engineering and Interface Passivation.

Abstract: Broadband photodetectors are of great importance for numerous optoelectronic applications. Two-dimensional (2D) tungsten disulfide (WS2), an important family member of transition-metal dichalcogenides (TMDs), has shown great potential for high-sensitivity photodetection due to its extraordinary properties. However, the inherent large bandgap of WS2 and the strong interface recombination impede the actualization of high-sensitivity broadband photodetectors. Here, we demonstrate the fabrication of an ultrabroadband WS2/Ge heterojunction photodetector through defect engineering and interface passivation. Thanks to the narrowed bandgap of WS2 induced by the vacancy defects, the effective surface modification with an ultrathin AlOx layer, and the well-designed vertical n-n heterojunction structure, the WS2/AlOx/Ge photodetector exhibits an excellent device performance in terms of a high responsivity of 634.5 mA/W, a large specific detectivity up to 4.3 × 1011 Jones, and an ultrafast response speed. Significantly, the device possesses an ultrawide spectral response spanning from deep ultraviolet (200 nm) to mid-wave infrared (MWIR) of 4.6 μm, along with a superior MWIR imaging capability at room temperature. The detection range has surpassed the WS2-based photodetectors in previous reports and is among the broadest for TMD-based photodetectors. Our work provides a strategy for the fabrication of high-performance ultrabroadband photodetectors based on 2D TMD materials.

Fabrication of non-polar GaN based highly responsive and fast UV photodetector

Abstract: We report the fabrication of ultraviolet photodetector on non-polar (11–20), nearly stress free, Gallium Nitride (GaN) film epitaxially grown on r-plane (1–102) sapphire substrate. High crystalline film leads to the formation of two faceted triangular islands like structures on the surface. The fabricated GaN ultraviolet photodetector exhibited a high responsivity of 340 mA/W at 5 V bias at room temperature which is the best performance reported for a-GaN/r-sapphire films. A detectivity of 1.24 × 109 Jones and noise equivalent power of 2.4 × 10−11 WHz−1/2 were also attained. The rise time and decay time of 280 ms and 450 ms have been calculated, respectively, which were the fastest response times reported for non-polar GaN ultraviolet photodetector. Such high performance devices substantiate that non-polar GaN can serve as an excellent photoconductive material for ultraviolet photodetector based applications.

Ultraflexible near-infrared organic photodetectors for conformal photoplethysmogram sensors

Abstract: Flexible organic optoelectronic devices simultaneously targeting mechanical conformability and fast responsivity in the near-infrared (IR) region are a prerequisite to expand the capabilities of practical optical science and engineering for on-skin optoelectronic applications. Here, an ultraflexible near-IR responsive skin-conformal photoplethysmogram sensor based on a bulk heterojunction photovoltaic active layer containing regioregular polyindacenodithiophene-pyridyl[2,1,3]thiadiazole-cyclopentadithiophene (PIPCP) is reported. The ultrathin (3 µm thick) photodetector exhibits unprecedented operational stability under severe mechanical deformation at a bending radius of less than 3 µm, even after more than 103 bending cycles. Deliberate optimization of the physical dimensions of the active layer used in the device enables precise on/off switching and high device yield simultaneously. The response frequency over 1 kHz under mechanically deformed conditions facilitates conformal electronic sensors at the machine/human interface. Finally, a mechanically stretchable, flexible, and skin-conformal photoplethysmogram (PPG) device with higher sensitivity than those of rigid devices is demonstrated, through conformal adherence to the flexuous surface of a fingerprint.