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Structural and optoelectronic characterization of Cu2CoSnS4 quaternary functional photodetectors
摘要： Al/p-Si/Cu2CoSnS4/Al quaternary functional semiconductor photodetectors showing solar detector properties were produced via sol-gel method. SEM, EDS and XRD techniques were used in the confirmation of the chemical composition of the photodiodes where nanoparticle like characteristics of Cu2CoSnS4 was seen. UV-vis spectroscopy was used in the investigation of optoelectronic characteristics. It was seen that photodiodes have a high absorption rate with minimum reflectance, bandgap energy was calculated as 1.19 eV. Current – time and current – voltage characteristics of the photodiodes revealed that photodiodes are sensitive to daylight; photodiodes present rectifying characteristics. Thermionic emission theory was used in the calculation of barrier height, ideality factor, photoresponse, photosensitivity, and linear dynamic rate characteristics. Capacitance – voltage, conductance – voltage, corrective capacitance – voltage, corrective conductance – voltage graphs were used to investigate the electrical properties of the Al/p-Si/Cu2CoSnS4/Al photodiodes. The electrical characteristics of the photodiodes reflect frequency dependent characteristics. Such a behaviour was found to be an indication of the existence of interface states. The density of interface (Dit) calculations revealed that the density of interface states strongly depends on AC signal frequency where diminished Dit was seen for increased signal frequency.
关键词： photodetector,photoresponse,Cu2NiSnS4 photodiodes,quaternary functional photodiodes,solar detectors
更新于2025-09-23 15:19:57
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Impact of Al2O3 stress liner on two-dimensional SnS2 nanosheet for photodetector application
摘要： Layered tin disulfide (SnS2) nanosheets are gradually coming into people’s vision as an emerging two-dimensional material for the potential application majority in optoelectronic field. We investigate a sample of ultra-thin SnS2 nanosheets (~5 nm) on SiO2/Si substrates and the photodetectors performance based on it with and without high-k ALD-Al2O3 stress liner. By means of temperature-dependent Raman spectroscopy, both a red-shift of Raman frequency from 313.1 cm-1 to 311.2 cm-1 as well as a reduction of the first order temperature coefficient from -0.01232 cm-1/K to -0.00895 cm-1/K are measured. For device, compared to SnS2 photodetector, Al2O3/SnS2 photodetector shows enhancement with 7-times light current, 10-times responsivity, 25%-off rising time and 70%-off falling time under 365 nm illumination. The phenomena can be rationalized by factors that the SnS2 sample suffers a tensile strain and passivation effect exerted by capped Al2O3 layer. Meanwhile, the first principle calculations assist the study from an angle of verification. The analogue stress treatment operated in this work improves the properties of SnS2 and enhances the performances of SnS2-based photodetectors, aiming at expanding the thin-film materials applications in optoelectronic devices.
关键词： Al2O3 stress liner,Photodetector,SnS2,Raman spectroscopy
更新于2025-09-23 15:19:57
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High quality silicon: Colloidal quantum dot heterojunction based infrared photodetector
摘要： The integration of silicon (Si) and nanomaterials with infrared light harvesting capability is a promising approach to fabricate large area infrared light detecting arrays. However, the construction of a high quality junction between Si and small bandgap colloidal quantum dots (CQDs) remains a challenge, which limited their photodetecting performance in the short wavelength infrared region (1.4 lm–3 lm). Herein, a layer of solution processed ZnO nanoparticles was inserted between silicon and CQDs to passivate the surface dangling bond of silicon. This signi?cantly reduces the carrier recombination between Si and CQDs. Meanwhile, the formation of the Si:CQD heterojunction structure enables effective carrier extraction. As a result, the photodetector shows the detecting range to the short wavelength infrared region (0.8 eV) and achieves a standard detectivity of 4.08 (cid:2) 1011 Jones at a bias of (cid:3)0.25 V at room temperature.
关键词： colloidal quantum dot,heterojunction,infrared photodetector,silicon
更新于2025-09-23 15:19:57
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Novel ultraviolet photodetector with ultrahigh photosensitivity employing SILAR-deposited ZnS film on MgZnO
摘要： A novel MgZnO/ZnS heterojunction-based ultraviolet (UV) photodetector (PD) with high performance is fabricated by a facile sol-gel process and a successive ionic layer adsorption and reaction (SILAR) method. ZnS is coated onto the MgZnO film as an interface modification layer, which overcomes the drawbacks of the pristine MgZnO photosensitive layer, such as lower carrier mobility and more traps in the material, and greatly enhances UV-light absorption. The type-II heterostructure constructed by work function differences near the interface facilitate the separation of photogenerated carriers. Compared with the MgZnO PD, the optimized heterojunction PD (MgZnO/ZnS-10) yields a dramatically decreased dark current (z1 nA), a remarkable responsivity (900 A/W) and an ultrahigh photo-to-dark current ratio (up to 2.3 (cid:1) 105) under 325 nm light illumination at 5 V bias. These results provide a cost-efficient means for improving the properties of MgZnO PDs, and show the advantages of MgZnO/ZnS heterojunction PDs in UV detection. This study demonstrates that rational construction of novel heterojunctions holds great potential for fabricating high-performance photodetectors.
关键词： Type-II heterostructure,MgZnO,Ultraviolet (UV) photodetector (PD),ZnS
更新于2025-09-23 15:19:57
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Dark-current reduction accompanied photocurrent enhancement in p-type MnO quantum-dot decorated n-type 2D-MoS <sub/>2</sub> -based photodetector
摘要： A highly crystalline single- or few-layered 2D-MoS2 induces a high dark current, due to which an extremely small photocurrent generated by a few photons can be veiled or distorted. In this report, we show that suppression in the dark current with the enhancement in the photocurrent of a 2D-based photodetector, which is a prerequisite for photoresponse enhancement, can be achieved by constructing an ideal p-n junction based on functionalizing n-type 2D-MoS2 with p-type quantum dots (QDs). Highly crystalline solution-processed manganese oxide QDs (MnO QDs) are synthesized via the pulsed femtosecond laser ablation technique in ethanol. The ablated MnO QDs are spray-coated on an exfoliated 2D-MoS2 substrate with interdigitated Au electrodes through N2-assisted spraying. In the resulting MnO QD-decorated 2D-MoS2 photodetector with a heterojunction, dark current is reduced and is accompanied by photocurrent enhancement, thereby markedly improving the photoresponsivity and detectivity of MoS2-based devices. To elucidate the underlying mechanisms contributing to this enhancement, power- and wavelength-dependent photoresponses, along with material characterizations based on spectroscopic, chemical, morphological measurements, and analyses, are discussed.
关键词： dark current,quantum dots,2D-MoS2,p-n junction,photodetector,photocurrent
更新于2025-09-23 15:19:57
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A Preamplifier for a CdHgTe Photodetector
摘要： A preamplifier for operation with an HgCdTe-based nitrogen-cooled IR photodetector (600 nm–15 μ m) is described. The preamplifier operates in the photoconductivity mode. The use of modern microcircuits made it possible to increase the bandwidth of the response to 2 MHz at a noise level of 0.5 nV/Hz1/2, which is close to the fundamental limit that is specified by the resistance of the photosensitive element. The preamplifier was used in an aperture-free scanning near-field optical microscope.
关键词： HgCdTe,IR photodetector,scanning near-field optical microscope,photoconductivity,preamplifier
更新于2025-09-23 15:19:57
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Resistive-type UVa??visible photodetector based on CdS NWs /ZnO nanowalls heterostructure fabricated using in-situ synthesis method
摘要： Here, the resistivity-type UV-visible photodetectors are designed and fabricated by implementation of direct integration between CdS nanowires(NWs) and vertical standing ZnO nanowalls with a facile in-situ synthesis method, in which ZnO nanowalls are employed as good support for anchoring well-dispersed CdS NWs to overcome its random distribution. The photodetectors based on CdS/ZnO heterojunctions demonstrate higher photo response activity than the prinstine CdS NWs and pure ZnO nanowalls photodetectors . The high performance could be attributed to the charge carrier separation efficiency and fast charge transportation facilitated by effective and close contact between CdS NWs and ZnO nanowalls. The results indicate that the ZnO/CdS heterojunctions fabricated by in-situ synthesis method provide a facile approach for nanoscale optoelectronic device.
关键词： photodetector,in-situ synthesis,CdS NWs,ZnO nanowalls
更新于2025-09-23 15:19:57
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Photon energy response optimization using few-channel spectroscopy dose method for Si-PIN photodetector applied in personal dose equivalent measurements
摘要： Si-PIN photodetectors having features such as low cost, small size, low weight, low voltage, and low power consumption are widely used as radiation detectors in electronic personal dosimeters (EPDs). The technical parameters of EPDs based on the Si-PIN photodetectors include photon energy response (PER), angular response, inherent error, and dose rate linearity. Among them, PER is a key parameter for evaluation of EPD measurement accuracy. At present, owing to the limitations of volume, power consumption, and EPD cost, the PER is usually corrected by a combination of single-channel counting techniques and filtering material methods. However, the above-mentioned methods have problems such as poor PER and low measurement accuracy. To solve such problems, in this study, a 1024-channel spectrometry system using a Si-PIN photodetector was developed and full-spectrum measurement in the reference radiation fields was conducted for radiation protection. The measurement results using the few-channel spectroscopy dose method showed that the PER could be controlled within ± 14% and ± 2% under the conditions of two and three energy intervals, respectively, with different channel numbers. The PER measured at 0° angle of radiation incidence meets the IEC 61526:2010 - 29% to +67% requirements of. Meanwhile, the channel number and counts-to-dose conversion factors formed in the experiment can be integrated into an EPD.
关键词： Si-PIN photodetector,Personal dose equivalent,Photon energy response,Electronic personal dosimeter,Few-channel spectroscopy dose method
更新于2025-09-23 15:19:57
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Inkjet-Printed Organohalide 2D Layered Perovskites for High-Speed Photodetectors on Flexible Polyimide Substrates
摘要： The synthesis of solution-processed two-dimensional organohalide layered (CH3(CH2)3NH3)2(CH3NH3)n?1PbnI3n+1 (n = 2, 3, and 4) perovskites is presented, where inkjet printing was used to fabricate heterostructure flexible photodetector (PD) devices on polyimide (PI) substrates. Inks for the n = 4 formulation were developed to inkjet-print PD devices that were photoresponsive to broadband incoming radiation in the visible regime, where the peak photoresponsivity R was calculated to be ～0.17 A/W, which is higher compared to prior reports, while the detectivity D was measured to be ～3.7 × 1012 Jones at a low light intensity F ≈ 0.6 mW/cm2. The ON/OFF ratio was also high (～2.3 × 103), while the response time τ on the rising and falling edges was measured to be τ ≈ 24 ms and τ ≈ 65 ms, respectively. Our strain-dependent measurements, conducted here for the first time for inkjet-printed perovskite PDs, revealed that the Ip decreased by only ～27% with bending (radius of curvature of ～0.262 cm?1). This work demonstrates the tremendous potential of the inkjet-printed, composition-tunable, organohalide 2D perovskite heterostructures for high-performance PDs, where the techniques are readily translatable toward flexible solar cell platforms as well.
关键词： organohalide 2D perovskites,flexible photodetector,inkjet printing,photoluminescence spectroscopy,strain dependency
更新于2025-09-23 15:19:57
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Purple-emissive carbon dots enhance sensitivity of Si photodetectors to ultraviolet range
摘要： In this work, we realized the synthesis of purple-emissive carbon dots (p-CDs) by a facile and highly reproducible route using folic acid as a sole precursor. The emission of the p-CDs is located around 390 nm, and independent of the excitation wavelength with a high photoluminescence quantum yield of 54.6%, thus complementing an emission color palette of brightly emitting carbon dots to a purple. Purple-emissive CDs are highly stable in both the colloidal state and in polymer films. A carbon dot luminescence down-shifting layer is used to sensitize a Si photodetector to UV range. As an example, p-CDs with an excitation maximum at 330 nm were integrated into Si photodetector, resulting in improving the photoresponsivity in a UV range from 0.8 to 2.5 mA/W, with a relative enhancement of 203.8%. This work represents a cheap, scalable and environmentally friendly way to create purple-emissive carbon dots enhancing the photoresponsivity of commercial photodetectors in a UV range thus being applicable in optical power meters, optical wireless communication systems, sunlight sensors, spectrophotometers, or radiation detectors.
关键词： UV range,Si photodetector,carbon dots,purple-emissive,photoluminescence
更新于2025-09-23 15:19:57