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Publications (7 of 7) Show all publications
Kumari, R., Gellanki, J., Kundale, S. S., Ustad, R. E., Dongale, T. D., Fu, Y., . . . Kumar, S. (2023). Artificial synaptic characteristics of PVA:ZnO nanocomposite memristive devices. APL Materials, 11(10), Article ID 101124.
Open this publication in new window or tab >>Artificial synaptic characteristics of PVA:ZnO nanocomposite memristive devices
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2023 (English)In: APL Materials, E-ISSN 2166-532X, Vol. 11, no 10, article id 101124Article in journal (Refereed) Published
Abstract [en]

Computational efficiency is significantly enhanced using artificial neural network-based computing. A two-terminal memristive device is a powerful electronic device that can mimic the behavior of a biological synapse in addition to storing information and performing logic operations. This work focuses on the fabrication of a memristive device that utilizes a resistive switching layer composed of polyvinyl alcohol infused with ZnO nanoparticles. By incorporating ZnO nanoparticles into the polymer film, the fabricated memristive devices exhibit functionalities that closely resemble those of biological synapses, including short-term and long-term plasticity, paired-pulse facilitation, and spike time-dependent plasticity. These findings establish the ZnO nanoparticle-polymer nanocomposite as a highly promising material for future neuromorphic systems. © 2023 Author(s).

Place, publisher, year, edition, pages
Melville: American Institute of Physics (AIP), 2023
Keywords
Activation energy, Computation theory, Computational efficiency, II-VI semiconductors, Memristors, Metal nanoparticles, Neural networks, Polymer films, Semiconducting films
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:hh:diva-51997 (URN)10.1063/5.0165205 (DOI)2-s2.0-85175313733 (Scopus ID)
Available from: 2023-11-14 Created: 2023-11-14 Last updated: 2023-11-16Bibliographically approved
Yager, T., Chikvaidze, G., Wang, Q. & Fu, Y. (2023). Graphene Hybrid Metasurfaces for Mid-Infrared Molecular Sensors. Nanomaterials, 13(14), Article ID 2113.
Open this publication in new window or tab >>Graphene Hybrid Metasurfaces for Mid-Infrared Molecular Sensors
2023 (English)In: Nanomaterials, E-ISSN 2079-4991, Vol. 13, no 14, article id 2113Article in journal (Refereed) Published
Abstract [en]

We integrated graphene with asymmetric metal metasurfaces and optimised the geometry dependent photoresponse towards optoelectronic molecular sensor devices. Through careful tuning and characterisation, combining finite-difference time-domain simulations, electron-beam lithography-based nanofabrication, and micro-Fourier transform infrared spectroscopy, we achieved precise control over the mid-infrared peak response wavelengths, transmittance, and reflectance. Our methods enabled simple, reproducible and targeted mid-infrared molecular sensing over a wide range of geometrical parameters. With ultimate minimization potential down to atomic thicknesses and a diverse range of complimentary nanomaterial combinations, we anticipate a high impact potential of these technologies for environmental monitoring, threat detection, and point of care diagnostics. © 2023 by the authors.

Place, publisher, year, edition, pages
Basel: MDPI, 2023
Keywords
gas sensor, graphene, metasurface, mid-infrared, photodetector
National Category
Other Physics Topics
Identifiers
urn:nbn:se:hh:diva-51381 (URN)10.3390/nano13142113 (DOI)001038823500001 ()2-s2.0-85166220463 (Scopus ID)
Projects
Towards a Universal Lab-on-Chip Sensor from a Single Graphene Sheet: from Photodetection to BiosensingEU CAMART2
Funder
Vinnova, 2020-00797EU, Horizon 2020, 739508
Note

Funding: This research was funded by the ERDF PostDoctoral Research Project No. 1.1.1.2/VIAA/4/20/740 (Towards a Universal Lab-on-Chip Sensor from a Single Graphene Sheet: from Photodetection to Biosensing), EU CAMART2 project (European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508) and Sweden’s innovation agency Vinnova (Large area CVD graphene-based sensors/IR-photodetectors 2020-00797). The APC was funded by the ERDF Project No. 1.1.1.2/VIAA/4/20/740.

Available from: 2023-08-14 Created: 2023-08-14 Last updated: 2023-08-14Bibliographically approved
Menegatti de Melo, F., Mattioni, J. V., Dias, F., Fu, Y. & Toma, H. E. (2021). Solvophobic-controlled synthesis of smartmagneto-fluorescent nanostructures for real-timeinspection of metallic fractures. Nanoscale Advances, 3(12), 3593-3604
Open this publication in new window or tab >>Solvophobic-controlled synthesis of smartmagneto-fluorescent nanostructures for real-timeinspection of metallic fractures
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2021 (English)In: Nanoscale Advances, E-ISSN 2516-0230, Vol. 3, no 12, p. 3593-3604Article in journal (Refereed) Published
Abstract [en]

The production of materials that contain more than one functional constituent, the so-calledmultifunctional materials, is quite relevant in advanced technology. By acting as building blocks,nanoparticles can be suitably explored for generating higher-order multifunctional structures. In thisregard, herein, a special clustered magneto-fluorescent superstructure has been developed for nondestructivedetection of flaws and shallow subsurface discontinuities in industrial ferromagneticmaterials. The strategy consists of the solvophobic-controlled assembly of organic-based maghemitecores and water-based II–VI quantum dots, in the presence of hexadecyltrimethyl-ammonium bromide,CTAB, as a compatibilizer agent. This composite exhibited a high magnetic response (smax ¼ 66 emug1) and uniform size, in addition to tunable optical properties (QY ¼ 78%). The strategy of utilizingnanoparticles as magneto-fluorescent nanoprobes to identify tiny slits represents a great advance, forimproving the capability of precisely revealing the fracture boundary locations by visual real-timeinspection. The nanoscale probes exhibit a low signal-to-noise ratio and a higher competitiveperformance in relation to the existing micrometric detection systems. © The Royal Society of Chemistry 2021.

Place, publisher, year, edition, pages
Cambridge: , 2021
Keywords
Iron-oxide nanoparticles, Quantum dots, Nanocrystals, Superlattices, Growth, Celles
National Category
Physical Sciences Chemical Sciences
Identifiers
urn:nbn:se:hh:diva-45377 (URN)10.1039/d1na00149c (DOI)000649778100001 ()2-s2.0-85107988317 (Scopus ID)
Available from: 2021-08-10 Created: 2021-08-10 Last updated: 2022-02-10Bibliographically approved
Fu, Y., Yager, T., Chikvaidze, G., Iyer, S. & Wang, Q. (2021). Time-resolved FDTD and experimental FTIR study of gold micropatch arrays for wavelength-selective mid-infrared optical coupling. Sensors, 21(15), Article ID 5203.
Open this publication in new window or tab >>Time-resolved FDTD and experimental FTIR study of gold micropatch arrays for wavelength-selective mid-infrared optical coupling
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2021 (English)In: Sensors, E-ISSN 1424-8220, Vol. 21, no 15, article id 5203Article in journal (Refereed) Published
Abstract [en]

Infrared radiation reflection and transmission of a single layer of gold micropatch two-dimensional arrays, of patch length similar to 1.0 mu m and width similar to 0.2 mu m, have been carefully studied by a finite-difference time-domain (FDTD) method, and Fourier-transform infrared spectroscopy (FTIR). Through precision design of the micropatch array structure geometry, we achieve a significantly enhanced reflectance (85%), a substantial diffraction (10%), and a much reduced transmittance (5%) for an array of only 15% surface metal coverage. This results in an efficient far-field optical coupling with promising practical implications for efficient mid-infrared photodetectors. Most importantly we find that the propagating electromagnetic fields are transiently concentrated around the gold micropatch array in a time duration of tens of ns, providing us with a novel efficient near-field optical coupling. © 2021 by the authors.

Place, publisher, year, edition, pages
Basel: MDPI, 2021
Keywords
FDTD, FTIR, metal micropatch arrays, near field optics, far field optics, nano fabrication, electron beam lithography, infrared sensing
National Category
Physical Sciences
Identifiers
urn:nbn:se:hh:diva-45376 (URN)10.3390/s21155203 (DOI)000682177800001 ()34372439 (PubMedID)2-s2.0-85111465509 (Scopus ID)
Funder
Vinnova, 2020-00797EU, Horizon 2020, 739508European Commission, 1.1.1.2/VIAA/4/20/740
Available from: 2021-08-10 Created: 2021-08-10 Last updated: 2022-02-10Bibliographically approved
Karimi, M., Heurlin, M., Limpert, S., Jain, V., Zeng, X., Geijselaers, I., . . . Pettersson, H. (2018). Intersubband Quantum Disc-in-Nanowire Photodetectors with Normal-Incidence Response in the Long-Wavelength Infrared [Letter to the editor]. Nano Letters, 18(1), 365-372
Open this publication in new window or tab >>Intersubband Quantum Disc-in-Nanowire Photodetectors with Normal-Incidence Response in the Long-Wavelength Infrared
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2018 (English)In: Nano Letters, ISSN 1530-6984, E-ISSN 1530-6992, Vol. 18, no 1, p. 365-372Article in journal, Letter (Refereed) Published
Abstract [en]

Semiconductor nanowires have great potential for realizing broadband photodetectors monolithically integrated with silicon. However, the spectral range of such detectors has so far been limited to selected regions in the ultraviolet, visible and near-infrared. Here, we report on the first intersubband nanowire heterostructure array photodetectors exhibiting a spectrally resolved photoresponse from the visible to long-wavelength infrared. In particular, the infrared response from 3-20 mm is enabled by intersubband transitions in low-bandgap InAsP quantum discs synthesized axially within InP nanowires. The intriguing optical characteristics, including unexpected sensitivity to normal incident radiation, are explained by excitation of the longitudinal component of optical modes in the photonic crystal formed by the nanostructured portion of the detectors. Our results provide a generalizable insight into how broadband nanowire photodetectors may be designed, and how engineered nanowire heterostructures open up new fascinating opportunities for optoelectronics.

Place, publisher, year, edition, pages
Washington: American Chemical Society (ACS), 2018
Keywords
Nanowires, infrared photodetectors, quantum discs, intersubband photodetectors, photonic crystals
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:hh:diva-35916 (URN)10.1021/acs.nanolett.7b04217 (DOI)000420000000049 ()2-s2.0-85040312470 (Scopus ID)
Available from: 2017-12-20 Created: 2017-12-20 Last updated: 2021-08-16Bibliographically approved
Shang, X., Yu, Y., Li, M., Wang, L., Zha, G., Ni, H., . . . Niu, Z. (2015). Effect of tunable dot charging on photoresponse spectra of GaAs p-i-n diode with InAs quantum dots. Journal of Applied Physics, 118(24), 244503-1-244503-9, Article ID 244503.
Open this publication in new window or tab >>Effect of tunable dot charging on photoresponse spectra of GaAs p-i-n diode with InAs quantum dots
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2015 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 118, no 24, p. 244503-1-244503-9, article id 244503Article in journal (Refereed) Published
Abstract [en]

Quantum dots (QDs)-embedded photodiodes have demonstrated great potential on detectors. A modulation of QD charging opens intriguing possibilities for adaptive sensing with bias-tunable detector characteristics. Here, we report on a p-i-n GaAs photodiode with InAs QDs whose charging is tunable due to unintentional Be diffusion and trap-assisted tunneling of holes, from bias- and temperature (T)-dependent photocurrent spectroscopy. For the sub-bandgap spectra, the T-dependent relative intensities "QD-s/WL" and "WL/GaAs" (WL: wetting layer) reflect a dominant tunneling under -0.9 V (trap-assisted tunneling from the top QDs) and a dominant thermal escape under -0.2 ~ 0.5 V (from the bottom QDs since the top ones are charged and inactive for optical absorption) from QD s-state, a dominant tunneling from WL and an enhanced QD charging at > 190 K (related to trap level ionization). For the above-bandgap spectra, the degradation of the spectral profile (especially that near GaAs bandedge) as the bias and T tune (especially under -0.2 ~ 0.2 V and at > 190 K) can be well explained by the enhanced photoelectron capture in QDs with tunable charging; the dominant spectral profile with no degradation under 0.5 V is due to a saturated electron capture in charged QDs (i.e. charging neutralization). QD level simulation and schematic bandstructures help to understand these effects. © 2015 AIP Publishing LLC

Place, publisher, year, edition, pages
Melville, NY: American Institute of Physics (AIP), 2015
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:hh:diva-30037 (URN)10.1063/1.4937408 (DOI)000367535100026 ()2-s2.0-84953857669 (Scopus ID)
Note

This work was supported by the National Key Basic Research Program of China (Grant No. 2013CB933304), Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB01010200), and the National Natural Science Foundation of China (Grant No. 61505196).

Available from: 2015-12-15 Created: 2015-12-15 Last updated: 2021-08-16Bibliographically approved
Shang, X.-J., He, J.-F., Li, M.-F., Zhan, F., Ni, H.-Q., Niu, Z.-C., . . . Fu, Y. (2011). Quantum-dot-induced optical transition enhancement in InAs quantum-dot-embedded p-i-n GaAs solar cells. Applied Physics Letters, 99(11), 113514-113514-3
Open this publication in new window or tab >>Quantum-dot-induced optical transition enhancement in InAs quantum-dot-embedded p-i-n GaAs solar cells
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2011 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 99, no 11, p. 113514-113514-3Article in journal (Refereed) Published
Abstract [en]

Photocurrents (PCs) of three p–i–n GaAs solar cells, sample A with InAs quantum dots (QDs) embedded in the depletion region, B with QDs in the n region, and C without QDs, were studied experimentally and theoretically. Above GaAs bandgap, the PC of A is increased, while B is decreased with respect to C, since in A, the QD-induced reflection of hole wave function increases its overlap with electron wave function so that the optical transition rate is enhanced, while carrier mobility in B is reduced due to QD-induced potential variations. Moreover, A and B have increased PCs in the sub-GaAs-bandgap range due to QD optical absorptions.

Place, publisher, year, edition, pages
New York, N.Y.: American Institute of Physics (AIP), 2011
Keywords
Efficiency, Photocurrent, Quantum dots, Solar cells, Well infrared photodetector
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Physical Sciences
Identifiers
urn:nbn:se:hh:diva-16457 (URN)10.1063/1.3638488 (DOI)000295034400089 ()2-s2.0-80053190661 (Scopus ID)
Available from: 2011-10-15 Created: 2011-10-15 Last updated: 2022-09-13Bibliographically approved
Projects
Megapixel - superlattice detectors with optical metasurfaces [ID21-0093]
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-2442-1809

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