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Karimi, M., Heurlin, M., Limpert, S., Jain, V., Mansouri, E., Zeng, X., . . . Pettersson, H. (2019). Nanowire photodetectors with embedded quantum heterostructures for infrared detection. Infrared physics & technology, 96, 209-212
Open this publication in new window or tab >>Nanowire photodetectors with embedded quantum heterostructures for infrared detection
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2019 (English)In: Infrared physics & technology, ISSN 1350-4495, E-ISSN 1879-0275, Vol. 96, p. 209-212Article in journal (Refereed) Published
Abstract [en]

Nanowires offer remarkable opportunities for realizing new optoelectronic devices because of their unique fundamental properties. The ability to engineer nanowire heterostructures with large bandgap variations is particularly interesting for technologically important broadband photodetector applications. Here we report on infrared photodetectors based on arrays of InP nanowires with embedded InAsP quantum discs. We demonstrate a strongly reduced dark current in the detector elements by compensating the unintentional n-doping in the nominal intrinsic region of the InP nanowires by in-situ doping with Zn, a crucial step towards realizing high-performance devices. The optimized array detectors show a broad spectral sensitivity at normal incidence for wavelengths from visible to far-infrared up to 20 μm, promoted by both interband and intersubband transitions. Optical simulations show that the unexpected normal incidence response at long wavelengths is due to non-zero longitudinal modes hosted by the nanowires. © 2018 Elsevier B.V.

Place, publisher, year, edition, pages
Amsterdam: Elsevier, 2019
Keywords
Nanowires, Infrared photodetectors, Quantum discs, Intersubband photodetectors
National Category
Nano Technology
Identifiers
urn:nbn:se:hh:diva-38531 (URN)10.1016/j.infrared.2018.11.009 (DOI)2-s2.0-85057545191 (Scopus ID)
Available from: 2018-12-10 Created: 2018-12-10 Last updated: 2019-01-14Bibliographically 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 (Print), 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 (Print), 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)
Available from: 2017-12-20 Created: 2017-12-20 Last updated: 2018-04-03Bibliographically approved
Karimi, M., Heurlin, M., Limpert, S., Borgstrom, M., Samuelson, L. & Pettersson, H. (2018). Long-wavelength intersubband quantum disc-in-nanowire photodetectors with normal incidence photoresponse. In: QSIP 2018: Abstracts. Paper presented at Quantum Structure Infrared Photodetectors Conference (QSIP 2018), Stockholm, Sweden, June 16-21, 2018 (pp. 55-55).
Open this publication in new window or tab >>Long-wavelength intersubband quantum disc-in-nanowire photodetectors with normal incidence photoresponse
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2018 (English)In: QSIP 2018: Abstracts, 2018, p. 55-55Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Semiconductor nanowire (NW) technology has emerged as a key facilitator of novel optoelectronics e.g. solar cells, photodetectors and LEDs. The functional wavelength range of current NW-based photodetectors is typically limited to the visible/ near-infrared region. In this work, we present the first ever reported electrical and optical characteristics of longwavelength IR photodetectors based on large square millimeter ensembles of vertically grown and processed InAsP/InP heterostructure NWs grown on InP substrates1 . More specifically, the MOVPE-grown NWs comprise single or multiple InAsP quantum discs (QDiscs) axially embedded in an n+-i-n+ geometry. The NWs are contacted together in a vertical geometry by uniformly depositing a thin insulating SiO2 layer, selective etching of the oxide from the tip of the NWs followed by sputtering of ITO as a common top contact to all NWs. Using Fourier transform photocurrent spectroscopy, we demonstrate a photoresponse extending from the visible to far infrared1,2. In particular, the infrared response from 3-20 μm is enabled by intersubband transitions in the lowbandgap InAsP quantum discs synthesized axially within the InP NWs. The detector elements exhibit an unexpected sensitivity to normal incident radiation, apparently in contradiction to well-known selection rules for intersubband transitions in quantum wells. From in-depth 2D and 3D optical simulations we attribute this result to an excitation of the longitudinal component of optical modes in the photonic crystal formed by the nanostructured portion of the detectors. Key advantages with the proposed design include a large degree of freedom in choice of material compositions, enhanced optical resonance effects due to periodically ordered NW arrays and the compatibility with silicon substrates. We believe that our novel detector design offers a route towards monolithic integration of compact and sensitive broadband III-V NW detectors with main-stream silicon technology which could seriously challenge existing commercially available photodetectors.

Keywords
nanowires, intersubband transitions, infrared photodetectors, photonic crystals
National Category
Nano Technology
Identifiers
urn:nbn:se:hh:diva-38635 (URN)
Conference
Quantum Structure Infrared Photodetectors Conference (QSIP 2018), Stockholm, Sweden, June 16-21, 2018
Available from: 2018-12-18 Created: 2018-12-18 Last updated: 2019-01-03Bibliographically approved
Jain, V., Heurlin, M., Karimi, M., Hussain, L., Aghaeipour, M., Nowzari, A., . . . Pettersson, H. (2017). Bias-dependent spectral tuning in InP nanowire-based photodetectors. Nanotechnology, 28(11), Article ID 114006.
Open this publication in new window or tab >>Bias-dependent spectral tuning in InP nanowire-based photodetectors
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2017 (English)In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 28, no 11, article id 114006Article in journal (Refereed) Published
Abstract [en]

Nanowire array ensembles contacted in a vertical geometry are extensively studied and considered strong candidates for next generations of industrial scale optoelectronics. Key challenges in this development deal with optimization of the doping profile of the nanowires and the interface between nanowires and transparent top contact. Here we report on photodetection characteristics associated with doping profile variations in InP nanowire array photodetectors. Bias-dependent tuning of the spectral shape of the responsivity is observed which is attributed to a Schottky-like contact at the nanowire-ITO interface. Angular dependent responsivity measurements, compared with simulated absorption spectra, support this conclusion. Furthermore, electrical simulations unravel the role of possible self-gating effects in the nanowires induced by the ITO/SiOx wrap-gate geometry. Finally, we discuss possible reasons for the observed low saturation current at large forward biases.  

Place, publisher, year, edition, pages
Bristol: Institute of Physics Publishing (IOPP), 2017
Keywords
nanowires, nanowire arrays, IR photodetectors, solar cells, nanophotonics
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:hh:diva-32769 (URN)10.1088/1361-6528/aa5236 (DOI)000395937500001 ()2-s2.0-85014564717 (Scopus ID)
Available from: 2016-12-20 Created: 2016-12-20 Last updated: 2018-04-25Bibliographically approved
Hussain, L., Karimi, M., Berg, A., Jain, V., Borgström, M. T., Gustafsson, A., . . . Pettersson, H. (2017). Defect-induced infrared electroluminescence from radial GaInP/AlGaInP quantum well nanowire array light- emitting diodes. Nanotechnology, 28(48), Article ID 485205.
Open this publication in new window or tab >>Defect-induced infrared electroluminescence from radial GaInP/AlGaInP quantum well nanowire array light- emitting diodes
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2017 (English)In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 28, no 48, article id 485205Article in journal (Refereed) [Artistic work] Published
Abstract [en]

Radial GaInP/AlGaInP nanowire array light-emitting diodes (LEDs) are promising candidates for novel high-efficiency solid state lighting due to their potentially large strain-free active emission volumes compared to planar LEDs. Moreover, by proper tuning of the diameter of the nanowires, the fraction of emitted light extracted can be significantly enhanced compared to that of planar LEDs. Reports so far on radial growth of nanowire LED structures, however, still point to significant challenges related to obtaining defect-free radial heterostructures. In this work, we present evidence of optically active growth-induced defects in a fairly broad energy range in vertically processed radial GaInP/AlGaInP quantum well nanowire array LEDs using a variety of complementary experimental techniques. In particular, we demonstrate strong infrared electroluminescence in a spectral range centred around 1 eV (1.2 μm) in addition to the expected red light emission from the quantum well. Spatially resolved cathodoluminescence studies reveal a patchy red light emission with clear spectral features along the NWs, most likely induced by variations in QW thickness, composition and barriers. Dark areas are attributed to infrared emission generated by competing defect-assisted radiative transitions, or to trapping mechanisms involving non-radiative recombination processes. Possible origins of the defects are discussed. © 2017 IOP Publishing Ltd

Place, publisher, year, edition, pages
Bristol: Institute of Physics Publishing Ltd., 2017
Keywords
radial core-shell nanowires, light-emitting diode, GaInP LED, nanowire LED, infrared emission, defect-induced emission
National Category
Nano Technology
Identifiers
urn:nbn:se:hh:diva-35497 (URN)10.1088/1361-6528/aa913c (DOI)000415052500002 ()2-s2.0-85033687191 (Scopus ID)
Available from: 2017-11-28 Created: 2017-11-28 Last updated: 2018-04-03Bibliographically approved
Karimi, M., Heurlin, M., Samuelson, L., Borgström, M. T. T. & Pettersson, H. (2017). Infrared Photodetectors Based on Nanowire Arrays – Towards Far Infrared Region. In: : . Paper presented at ICOPAP 2017 : 19th International Conference on Optoelectronics, Photonics and Applied Physics, October 23-24, 2017. WASET
Open this publication in new window or tab >>Infrared Photodetectors Based on Nanowire Arrays – Towards Far Infrared Region
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2017 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Nanowire semiconductors are promising candidates for optoelectronic applications such as solar cells, photodetectors and lasers due to their quasi-1D geometry and large surface to volume ratio. The functional wavelength range of NW-based detectors is typically limited to the visible/near-infrared region. In this work, we present electrical and optical properties of novel IR photodetectors based on large square millimeter ensembles (>1million) of vertically processed semiconductor heterostructure nanowires (NWs) grown on InP substrates which operates in longer wavelengths. InP NWs comprising single or multiple (20) InAs/InAsP QDics axially embedded in an n-i-n geometry, have been grown on InP substrates using MOVPE. The NWs are contacted in vertical direction by ALD deposition of 50 nm SiO2 as an insulating layer followed by sputtering of ITO and evaporation of Ti and Au as top contact layer. In order to extend the sensitivity range to the mid-wavelength and long-wavelength regions, the intersubband transition within conduction band of InAsP QDisc is suggested. We present first experimental indications of intersubband photocurrent in NW geometry and discuss important design parameters for realization of intersubband detectors. Key advantages with the proposed design include large degree of freedom in choice of materials compositions, possible enhanced optical resonance effects due to periodically ordered NW arrays and the compatibility with silicon substrates. We believe that our novel detector design offers the route towards monolithic integration of compact and sensitive III-V NW long wavelength detectors with Si technology.

Place, publisher, year, edition, pages
WASET, 2017
Keywords
Intersubband photodetector, Infrared, Nanowire, Quantum Disc
National Category
Nano Technology
Identifiers
urn:nbn:se:hh:diva-35496 (URN)
Conference
ICOPAP 2017 : 19th International Conference on Optoelectronics, Photonics and Applied Physics, October 23-24, 2017
Available from: 2017-11-28 Created: 2017-11-28 Last updated: 2018-04-03Bibliographically approved
Jain, V., Heurlin, M., Barrigon, E., Bosco, L., Nowzari, A., Schroff, S., . . . Pettersson, H. (2017). InP/InAsP Nanowire-Based Spatially Separate Absorption and Multiplication Avalanche Photodetectors. ACS Photonics, 4(11), 2693-2698
Open this publication in new window or tab >>InP/InAsP Nanowire-Based Spatially Separate Absorption and Multiplication Avalanche Photodetectors
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2017 (English)In: ACS Photonics, E-ISSN 2330-4022, Vol. 4, no 11, p. 2693-2698Article in journal (Refereed) Published
Abstract [en]

Avalanche photodetectors (APDs) are key components in optical communication systems due to their increased photocurrent gain and short response time as compared to conventional photodetectors. A detector design where the multiplication region is implemented in a large band gap material is desired to avoid detrimental Zener tunneling leakage currents, a concern otherwise in smaller band gap materials required for absorption at 1.3/1.55 μm. Self-assembled III-V semiconductor nanowires offer key advantages such as enhanced absorption due to optical resonance effects, strain-relaxed heterostructures, and compatibility with mainstream silicon technology. Here, we present electrical and optical characteristics of single InP and InP/InAsP nanowire APD structures. Temperature-dependent breakdown characteristics of p+-n-n+ InP nanowire devices were investigated first. A clear trap-induced shift in breakdown voltage was inferred from I-V measurements. An improved contact formation to the p+-InP segment was observed upon annealing, and its effect on breakdown characteristics was investigated. The band gap in the absorption region was subsequently varied from pure InP to InAsP to realize spatially separate absorption and multiplication APDs in heterostructure nanowires. In contrast to the homojunction APDs, no trap-induced shifts were observed for the heterostructure APDs. A gain of 12 was demonstrated for selective optical excitation of the InAsP segment. Additional electron-beam-induced current measurements were carried out to investigate the effect of local excitation along the nanowire on the I-V characteristics. Simulated band profiles and electric field distributions support our interpretation of the experiments. Our results provide important insight for optimization of avalanche photodetector devices based on III-V nanowires. © 2017 American Chemical Society

Place, publisher, year, edition, pages
Washington: American Chemical Society (ACS), 2017
Keywords
avalanche photodetectors, nanowires, punch-through, SAM APDs
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:hh:diva-36687 (URN)10.1021/acsphotonics.7b00389 (DOI)000415786300010 ()2-s2.0-85034033359 (Scopus ID)
Funder
Swedish Energy AgencyCarl Tryggers foundation Swedish Research CouncilSwedish Foundation for Strategic Research
Note

The authors acknowledge financial support from NanoLund, the Swedish Research Council, the Swedish National Board for Industrial and Technological Development, the Swedish Foundation for Strategic Research, the Ljungberg Foundation, the Carl Trygger Foundation, and the Swedish Energy Agency. This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 641023 (NanoTandem) and under the Marie Sklodowska-Curie grant agreement No. 656208.

Available from: 2018-04-26 Created: 2018-04-26 Last updated: 2018-06-14Bibliographically approved
Karimi, M., Heurlin, M., Samuelson, L., Borgström, M. T. & Pettersson, H. (2017). Intersubband Photodetectors Realized with InAsP/InP Quantum Discs-in-Nanowire Heterostructures. In: : . Paper presented at Nanowire Week, Lund, Sweden, May 29th-June 2nd, 2017.
Open this publication in new window or tab >>Intersubband Photodetectors Realized with InAsP/InP Quantum Discs-in-Nanowire Heterostructures
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2017 (English)Conference paper, Poster (with or without abstract) (Other academic)
National Category
Nano Technology
Identifiers
urn:nbn:se:hh:diva-34049 (URN)
Conference
Nanowire Week, Lund, Sweden, May 29th-June 2nd, 2017
Available from: 2017-06-10 Created: 2017-06-10 Last updated: 2018-04-03Bibliographically approved
Kivisaari, P., Berg, A., Karimi, M., Storm, K., Limpert, S., Oksanen, J., . . . Borgström, M. T. (2017). Optimization of Current Injection in AlGaInP Core−Shell Nanowire Light-Emitting Diodes. Nano letters (Print), 17(6), 3599-3606
Open this publication in new window or tab >>Optimization of Current Injection in AlGaInP Core−Shell Nanowire Light-Emitting Diodes
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2017 (English)In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 17, no 6, p. 3599-3606Article in journal (Refereed) Published
Abstract [en]

Core–shell nanowires offer great potential to enhance the efficiency of light-emitting diodes (LEDs) and expand the attainable wavelength range of LEDs over the whole visible spectrum. Additionally, nanowire (NW) LEDs can offer both improved light extraction and emission enhancement if the diameter of the wires is not larger than half the emission wavelength (λ/2). However, AlGaInP nanowire LEDs have so far failed to match the high efficiencies of traditional planar technologies, and the parameters limiting the efficiency remain unidentified. In this work, we show by experimental and theoretical studies that the small nanowire dimensions required for efficient light extraction and emission enhancement facilitate significant loss currents, which result in a low efficiency in radial NW LEDs in particular. To this end, we fabricate AlGaInP core–shell nanowire LEDs where the nanowire diameter is roughly equal to λ/2, and we find that both a large loss current and a large contact resistance are present in the samples. To investigate the significant loss current observed in the experiments in more detail, we carry out device simulations accounting for the full 3D nanowire geometry. According to the simulations, the low efficiency of radial AlGaInP nanowire LEDs can be explained by a substantial hole leakage to the outer barrier layer due to the small layer thicknesses and the close proximity of the shell contact. Using further simulations, we propose modifications to the epitaxial structure to eliminate such leakage currents and to increase the efficiency to near unity without sacrificing the λ/2 upper limit of the nanowire diameter. To gain a better insight of the device physics, we introduce an optical output measurement technique to estimate an ideality factor that is only dependent on the quasi-Fermi level separation in the LED. The results show ideality factors in the range of 1–2 around the maximum LED efficiency even in the presence of a very large voltage loss, indicating that the technique is especially attractive for measuring nanowire LEDs at an early stage of development before electrical contacts have been optimized. The presented results and characterization techniques form a basis of how to simultaneously optimize the electrical and optical efficiency of core–shell nanowire LEDs, paving the way to nanowire light emitters that make true use of larger-than-unity Purcell factors and the consequently enhanced spontaneous emission. © 2017American Chemical Society

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
National Category
Nano Technology
Identifiers
urn:nbn:se:hh:diva-34048 (URN)10.1021/acs.nanolett.7b00759 (DOI)000403631600041 ()28535346 (PubMedID)2-s2.0-85020753897 (Scopus ID)
Available from: 2017-06-10 Created: 2017-06-10 Last updated: 2018-04-03Bibliographically approved
Karimi, M., Jain, V., Heurlin, M., Nowzari, A., Hussain, L., Lindgren, D., . . . Pettersson, H. (2017). Room-temperature InP/InAsP Quantum Discs-in-Nanowire Infrared Photodetectors [Letter to the editor]. Nano letters (Print), 17(6), 3356-3362
Open this publication in new window or tab >>Room-temperature InP/InAsP Quantum Discs-in-Nanowire Infrared Photodetectors
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2017 (English)In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 17, no 6, p. 3356-3362Article in journal, Letter (Refereed) Published
Abstract [en]

The possibility to engineer nanowire heterostructures with large bandgap variations is particularly interesting for technologically important broadband photodetector applications. Here we report on a combined study of design, fabrication, and optoelectronic properties of infrared photodetectors comprising four million n+–i–n+ InP nanowires periodically ordered in arrays. The nanowires were grown by metal–organic vapor phase epitaxy on InP substrates, with either a single or 20 InAsP quantum discs embedded in the i-segment. By Zn compensation of the residual n-dopants in the i-segment, the room-temperature dark current is strongly suppressed to a level of pA/NW at 1 V bias. The low dark current is manifested in the spectrally resolved photocurrent measurements, which reveal strong photocurrent contributions from the InAsP quantum discs at room temperature with a threshold wavelength of about 2.0 μm and a bias-tunable responsivity reaching 7 A/W@1.38 μm at 2 V bias. Two different processing schemes were implemented to study the effects of radial self-gating in the nanowires induced by the nanowire/SiOx/ITO wrap-gate geometry. Summarized, our results show that properly designed axial InP/InAsP nanowire heterostructures are promising candidates for broadband photodetectors. © 2017 American Chemical Society.

Place, publisher, year, edition, pages
Washington, DC: American Chemical Society (ACS), 2017
Keywords
Nanowires, disc-in-nanowire, infrared photodetectors, quantum discs
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:hh:diva-34047 (URN)10.1021/acs.nanolett.6b05114 (DOI)000403631600005 ()28535059 (PubMedID)2-s2.0-85020825146 (Scopus ID)
Available from: 2017-06-10 Created: 2017-06-10 Last updated: 2018-04-03Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-3160-8540

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