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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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Facile synthesis of tin monosulfide nanosheets via physical vapour deposition and their near-infrared photoresponse
摘要： Two-dimensional layered materials (TDLMs), such as tin sulfide (SnS2), have attracted significant attention due to their vast potential applications in the fields of electronics, optoelectronics, energy conversion, and storage. Tin monosulfide (SnS) is an intrinsic p-type semiconductor in the family of TDLMs. Further explorations of SnS requires the development of efficient synthesis techniques. Here, we report SnS nanosheets grown via a physical vapour deposition (PVD) approach. The morphology was characterized using Raman spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). These SnS nanosheets exhibit a square shape with a smooth surface having an average lateral size of 7 μm and a thickness of 12 nm. No impurities were observed in the SnS nanosheets. Furthermore, photodetectors based on such SnS nanosheets were fabricated. The results show that the as-grown SnS has an excellent photo-response performance for an 850-nm laser with a high responsivity of 1604 AW-1, an external quantum efficiency of 2.34 × 105% and a detectivity of 3.42 × 1011 jones, which are larger than those values reported for previous SnS-based photodetectors. Moreover, the rise and fall times are 7.6 and 29.9 ms, respectively. Our work provides a strategy to obtain high-purity and ultrathin SnS while indicating that SnS has a great potential in applications for near-infrared photodetectors.
关键词： near-infrared photoresponse,tin monosulfide,nanosheets,physical vapour deposition
更新于2025-09-11 14:15:04