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| 2. |
- Flodgren, Vidar, et al.
(författare)
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III-V nanowire based neuromorphic nanophotonic circuits
- 2023
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Ingår i: 2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023. - 9798350345995
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Konferensbidrag (refereegranskat)abstract
- Combining highly efficient nanophotonic structures into artificial neural networks hold significant promise for superior hardware solutions [1]. Well-defined circuit architectures and concepts, with limited size and clear functionality are useful to develop and verify such novel concepts. Insects are capable of amazing autonomous feats well beyond current computers, such as navigating across hundreds of kilometres of unfamiliar terrain, with only a few drops of nectar as energy supply. One important module of the insect brain, conserved across species with vastly different lifestyles, is the central complex navigation circuit. This has been distilled to its fundamental neuroarchitecture and the function of a number of its components into a biologically constrained computational model [2].
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| 3. |
- Moberg, Christina, et al.
(författare)
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De unga gör helt rätt när de stämmer staten
- 2022
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Ingår i: Aftonbladet. - 1103-9000.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- 1 620 forskare och lärare i forskarvärlden: Vi ställer oss bakom Auroras klimatkrav
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| 4. |
- Adham, Kristi, et al.
(författare)
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Growth of branched nanowires via solution-based Au seed particle deposition
- 2023
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Ingår i: Materials Research Express. - 2053-1591. ; 10:8
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Tidskriftsartikel (refereegranskat)abstract
- Nanowires offer unprecedented flexibility as nanoscale building blocks for future optoelectronic devices, especially with respect to nanowire solar cells and light-emitting diodes. A relatively new concept is that of charge carrier diffusion-induced light-emitting diodes, for which nanowires offer an interesting architecture by use of particle-assisted core-branch growth. The branches should be homogenously distributed along the cores. However, most deposition techniques, such as aerosol particle deposition, mainly yield particles at the nanowire tips for dense nanowire arrays. In this study, we demonstrate a liquid-based approach for homogeneously distributed formation of catalytic Au particles on the core nanowire sidewalls which is cost and time-efficient. Subsequently, we demonstrate the synthesis of dispersed nanowire branches. We show that by changing the deposition parameters, we can tune the number of branches, their dimensions, and their growth direction.
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| 5. |
- Alcer, David, et al.
(författare)
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Comparison of Triethylgallium and Trimethylgallium Precursors for GaInP Nanowire Growth
- 2021
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Ingår i: Physica Status Solidi (B) Basic Research. - : Wiley. - 0370-1972. ; 258:2
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Tidskriftsartikel (refereegranskat)abstract
- Nanowire (NW) arrays containing a top segment of GaxIn1–xP are investigated, comparing NWs grown using two different Ga precursors, trimethylgallium (TMGa) and triethylgallium (TEGa). TMGa is the precursor commonly used for the particle-assisted vapor–liquid–solid (VLS) growth of GaxIn1–xP NWs. However, it shows inefficient pyrolysis at typical NW growth conditions. The use of the alternative precursor TEGa is investigated by making a direct comparison between NWs grown using TEGa and TMGa at otherwise identical growth conditions. Growth rates, resulting NW materials composition, and time-resolved photoluminescence (TRPL) lifetimes are investigated. With increasing Ga content of the NWs, the TRPL lifetimes decrease, indicating trap states that are associated with GaP. Somewhat longer TRPL lifetimes for the samples grown using TEGa indicate a lower concentration of deep trap states. For doped NWs, it is found that the strong effect of the p-type dopant diethylzinc (DEZn) on the NW composition, observed for GaxIn1–xP NWs grown using TMGa, is absent when using TEGa.
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| 6. |
- Alcer, David, et al.
(författare)
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Processing and characterization of large area InP nanowire photovoltaic devices
- 2023
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Ingår i: Nanotechnology. - 0957-4484. ; 34:29
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Tidskriftsartikel (refereegranskat)abstract
- III−V nanowire (NW) photovoltaic devices promise high efficiencies at reduced materials usage. However, research has so far focused on small devices, mostly ≤1 mm2. In this study, the upscaling potential of axial junction InP NW photovoltaic devices is investigated. Device processing was carried out on a full 2″ wafer, with device sizes up to 1 cm2, which is a significant increase from the mm-scale III−V NW photovoltaic devices published previously. The short-circuit current density of the largest 1 cm2 devices, in which 460 million NWs are contacted in parallel, is on par with smaller devices. This enables a record power generation of 6.0 mW under AM1.5 G illumination, more than one order of magnitude higher than previous III−V NW photovoltaic devices. On the other hand, the fill factor of the larger devices is lower in comparison with smaller devices, which affects the device efficiency. By use of electroluminescence mapping, resistive losses in the indium tin oxide (ITO) front contact are found to limit the fill factor of the large devices. We use combined light-beam induced current (LBIC) and photoluminescence (PL) mapping as a powerful characterization tool for NW photovoltaic devices. From the LBIC and PL maps, local defects can be identified on the fully processed devices.
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| 7. |
- Alcer, David
(författare)
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Single Junction and Tandem Junction Nanowire Solar Cells
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Solar cells based on silicon are successfully harvesting solar energy in established and increasingly widespread solar panels. However, their efficiency is limited by the Shockley–Queisser limit. For certain applications where high efficiency is the key figure of merit, the use of multi-junction solar cells is desirable.III–V multi-junction solar cells exhibit the highest efficiencies achieved to date, but suffer from the high cost of the III–V materials.Arrays of III–V nanowires show strong light absorption while covering only a small fraction of the surface, minimizing materials consumption. Therefore, solar cells made from III–V nanowire arrays are a possible candidate to achieve high efficiencies at a fraction of the cost of traditional planar III–V solar cells. This thesis aims to contribute to the development of III–V nanowire solar cells by addressing some of the challenges the technology is facing.Concerning single junction nanowire solar cells, Paper I investigates the effects of the device size on the performance. In contrast to the commonly used devices in nanowire solar cell research with an area below 1×1mm2, significantly larger devices with an area of 10×10 mm² were processed, and the effects of device size on the external quantum efficiency (EQE) and J–V characteristics are investigated.A concept of optically transparent nanowire solar cells which can absorb near-infrared radiation is presented in Paper II.In the realm of nanowire synthesis, Paper III is a comparative study of two different Ga precursors to establish favorable conditions for the growth of GaInP nanowire segments. Paper IV reports on the successful processing of tandem junction nanowire solar cells based on a GaInP top junction and an InP bottom junction, connected by an Esaki tunnel diode.
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| 8. |
- Alcer, David, et al.
(författare)
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Vertically Processed GaInP/InP Tandem-Junction Nanowire Solar Cells
- 2024
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Ingår i: ACS Applied Nano Materials. - 2574-0970. ; 7:2, s. 2352-2358
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Tidskriftsartikel (refereegranskat)abstract
- We present vertically processed photovoltaic devices based on GaInP/InP tandem-junction III-V nanowires (NWs), contacting approximately 3 million NWs in parallel for each device. The GaInP and InP subcells as well as the connecting Esaki tunnel diode are all realized within the same NW. By processing GaInP/InP tandem-junction NW solar cells with varying compositions of the top junction GaInP material, we investigate the impact of the GaInP composition on the device performance. External quantum efficiency (EQE) measurements on devices with varying GaInP composition provide insights into the performance of the respective subcells, revealing that the GaInP subcell is current-limiting for all devices. I-V measurements under AM1.5G illumination confirm voltage addition of the subcells, resulting in an open-circuit voltage of up to 1.91 V. However, the short-circuit current density is low, ranging between 0.24 and 3.44 mA/cm2, which leads to a resulting solar conversion efficiency of up to 3.60%. Our work shows a path forward toward high-efficiency NW photovoltaics and identifies critical issues that need improvement.
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| 9. |
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| 10. |
- Chen, Yang, et al.
(författare)
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Semiconductor nanowire array for transparent photovoltaic applications
- 2021
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 118:19
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Tidskriftsartikel (refereegranskat)abstract
- The surface area of a building that could potentially be used for Building Integrated Photovoltaics would increase dramatically with the availability of transparent solar cells that could replace windows. The challenge is to capture energy from outside the visible region (UV or IR) while simultaneously allowing a high-quality observation of the outside world and transmitting sufficient light in the visible region to satisfactorily illuminate the interior of the building. In this paper, we show both computationally and experimentally that InP nanowire arrays can have good transparency in the visible region and high absorption in the near-infrared region. We show experimentally that we can achieve mean transparencies in the visible region of 65% and the radiative limit of more than 10% based on measured absorption and calculated emission. Our results demonstrate that nanowire arrays hold promise as a method to achieve transparent solar cells, which would fulfill the requirements to function as windows. In addition, we show that by optical design and by designing the geometry of nanowire arrays, solar cells can be achieved that absorb/transmit at wavelengths that are not decided by the bandgap of the material and that can be tailored to specific requirements such as colorful windows.
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