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Carrier transport and recombination dynamics of InAs/GaAs sub-monolayer quantum dot near infrared photodetector
摘要： Here, we present a relative study of tunnel-induced photocarrier escape processes in a laterally coupled InAs sub-monolayer quantum dot-based photodetector (SML QD-PD) as a function of fractional coverage from 0.4 ML to 0.8 ML. Both by simulation and experiment, we have quantitatively described the temperature dependent interband photoresponse spectrally tuned in the near infrared region (835 nm–890 nm) on the basis of mutual competition between the interband carrier recombination and interdot tunneling lifetime with varying SML coverage. The progressively increasing recombination lifetime and decreasing interdot tunneling lifetime with increasing SML coverage has attributed to a faster photoresponse and greater responsivity. At higher coverage fraction, tunnel induced fast speed photocarrier transit through lateral array of SML QDs has been found to be capable of offering a faster temporal response (100 μs) with faithful reproducibility up to higher frequencies (1.3 KHz). Here, we report a powerful strategy to simultaneously tune responsivity, speed of time response and detectivity by externally controlling the SML coverage. This time response is measured to be nine times faster than a conventional SK QD photodetector. With increased coverage, inhibition of dark current due to trapping of injected charge carriers up to higher temperatures have resulted in high sustainable photodetectivity of 8 × 1011 cm Hz1/2 w?1 at ~250 K that offers near room temperature photodetection.
关键词： photoconductive gain,quantum dot photodetector,inter-dot tunneling,submonolayer coverage,near-infrared photoresponse,recombination dynamics,temporal photoresponse
更新于2025-09-23 15:19:57
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Anion Engineering Enhanced Response Speed and Tunable Spectral Responsivity in Gallium-Oxynitrides-Based Ultraviolet Photodetectors
摘要： Most of the currently developed Ga2O3-based solar blind photodetectors exhibit unexpected high persistent photoconductive gain at the expense of low response speed, and thus, the suppression of carrier trapping remains challenging. In this work, we demonstrated amorphous gallium-oxynitride-based (GaON) ultraviolet photodetectors with tunable spectral response and enhanced response speed by in situ anion engineering with a reactive sputtering technique. The tunable spectral response from 4.95 to 4.37 eV is a result of a bandgap narrowing effect, attributed to the elevation of the valence band maximum (VBM) by the hybridization of N 2p and O 2p states and the enhanced p-d repulsion. The constructed GaON PDs with a proper nitrogen composition exhibit remarkably reduced dark current and a fast response time of about 100 μs. Oxygen vacancies are deactivated by the lift-up of VBM so that slow carrier detrapping processes are suppressed, resulting in the reduced persistent photoconductivity and improved response speed. Meanwhile, nitrogen introduction increases the recombination and scattering probabilities of photoexcited carriers, which results in the reduced photoresponsivity. Thus, the rational design through anion engineering allows a flexibility in bandgap modulation and suppression of carrier trapping in oxynitrides, which provides an alternative strategy to achieve high-speed ultraviolet photodetectors.
关键词： ultraviolet photodetectors,gallium oxynitrides,bandgap modulation,photoconductive gain,anion engineering
更新于2025-09-23 15:19:57
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Industrial Applications of Nanomaterials || Nanomaterials-based UV photodetectors
摘要： Photodetectors are essential elements applied in video imaging, optical communications, biomedical imaging, security, night-vision, gas sensing, and motion detection, which possess the ability to transform light into electrical signals precisely. As the scale and diversity of application areas are growing, the need for innovative photodetection platform technologies with higher performance in terms of speed, efficiency or wavelength range, as well as material flexibility, transparency, and complementary metal-oxide-semiconductor (CMOS) integrability, is becoming more critical. In the past decades, extensive efforts have been devoted to explore the next generation of photodetector materials, such as In2Te3, ZnO, and GaN, with low noise, high photosensitivity, and good stability. However, many of these novel photodetector materials still suffer from limited photocurrent and photoresponse speed.
关键词： Nanomaterials,Schottky contacts,photoconductive gain,photodetection mechanism,photoresistors,linear dynamic range,responsivity,external quantum efficiency,photodiodes,specific detectivity,UV photodetectors
更新于2025-09-19 17:13:59
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Spectral responsivity and photoconductive gain in thin film black phosphorus photodetectors
摘要： We have fabricated black phosphorus photodetectors and characterized their full spectral responsivity. These devices, which are effectively in the bulk thin film limit, show broadband responsivity ranging from <400 nm to the ~3.8 μm bandgap. In the visible, an intrinsic responsivity >6 A/W can be obtained due to internal gain mechanisms. By examining the full spectral response, we identify a sharp contrast between the visible and infrared behavior. In particular, the visible responsivity shows a large photoconductive gain and gate-voltge dependence, while the infrared responsivity is nearly independent of gate voltage and incident light intensity under most conditions. This is attributed to a contribution from the surface oxide. In addition, we find that the polarization anisotropy in responsivity along armchair and zigzag directions can be as large as 103 and extends from the band edge to 500 nm. The devices were fabricated in an inert atmosphere and encapsulated by Al2O3 providing stable operation for more than 6 months.
关键词： Two-dimensional materials,Mid-infrared,Photodetectors,Black phosphorus,Photoconductive gain
更新于2025-09-12 10:27:22