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Träfflista för sökning "L773:0040 6090 OR L773:1879 2731 ;pers:(Edoff Marika 1965)"

Sökning: L773:0040 6090 OR L773:1879 2731 > Edoff Marika 1965

  • Resultat 1-8 av 8
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1.
  • Bose, Sourav, et al. (författare)
  • A morphological and electronic study of ultrathin rear passivated Cu(In,Ga)Se2 solar cells
  • 2019
  • Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 671, s. 77-84
  • Tidskriftsartikel (refereegranskat)abstract
    • The effects of introducing a passivation layer at the rear of ultrathin Copper Indium Gallium di-Selenide Cu(In,Ga)Se2 (CIGS) solar cells is studied. Point contact structures have been created on 25 nm Al2O3 layer using e-beam lithography. Reference solar cells with ultrathin CIGS layers provide devices with average values of light to power conversion efficiency of 8.1% while for passivated cells values reached 9.5%. Electronic properties of passivated cells have been studied before, but the influence of growing the CIGS on Al2O3 with point contacts was still unknown from a structural and morphological point of view. Scanning Electron Microscopy, X-ray Diffraction and Raman spectroscopy measurements were performed. These measurements revealed no significant morphological or structural differences in the CIGS layer for the passivated samples compared with reference samples. These results are in agreement with the similar values of carrier density (~8 x 1016 cm-3) and depletion region (~160 nm) extracted using electrical measurements. A detailed comparison between both sample types in terms of current-voltage, external quantum efficiency and photoluminescence measurements show very different optoelectronic behaviour which is indicative of a successful passivation. SCAPS simulations are done to explain the observed results in view of passivation of the rear interface.
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2.
  • Böhnke, Tobias, et al. (författare)
  • Copper indium gallium diselenide thin films for sun angle detectors in space applications
  • 2009
  • Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 517:6, s. 2063-2068
  • Tidskriftsartikel (refereegranskat)abstract
    • This work reports on processing, analysis and characterization of copper indium gallium diselenide (CIGS)used as a photosensitive layer for sensors such as sun angle detectors in space applications. CIGS-based solarcell devices with different CIGS layer thicknesses and the pn-junction located on the opposite side of theincidence of light were illuminated through their ultra-thin transparent molybdenum back contacts. Theresults from the current density versus voltage and quantum efficiency measurement indicate that the CIGSabsorber layer may not exceed 750 nm at backside illumination, due to the limited CIGS diffusion length.
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3.
  • Igalson, M., et al. (författare)
  • Concentration of defects responsible for persistent photoconductivity in Cu (In,Ga)Se-2 : Dependence on material composition
  • 2019
  • Ingår i: Thin Solid Films. - : ELSEVIER SCIENCE SA. - 0040-6090 .- 1879-2731. ; 669, s. 600-604
  • Tidskriftsartikel (refereegranskat)abstract
    • Persistent photoconductivity (PPC) in thin Cu(In,Ga)Se-2 films is discussed within a model of relaxing defects acting as donors or acceptors depending on their configurational and charge state. The aim of this work is to identify the factors related to technological processes which affect the magnitude of PPC. We established a method of evaluation of the concentration of metastable defects in thin Cu(In,Ga)Se-2 films relating it to the position of the Fermi level in thermodynamic equilibrium and used it to compare and discuss the impact of preparation details on the PPC value. The main result is that deviation from Cu/(Ga + In) stoichiometry does not change the concentration of metastable defects. Post deposition annealing in selenium affects the PPC depending on the presence of sodium during the treatment, while the impact of sodium itself on the metastable defect concentration apparently depends on whether it is present during the Cu(In,Ga)Se-2 deposition process or whether it is supplied during post-deposition treatment.
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4.
  • Igalson, Margaret, et al. (författare)
  • Reinterpretation of defect levels derived from capacitance spectroscopy of CIGSesolar cells
  • 2009
  • Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 517:7, s. 2153-2157
  • Tidskriftsartikel (refereegranskat)abstract
    • In this work we make an attempt to clarify ambiguities and to present our present understanding of defectsand defect-related phenomena affecting the capacitance characteristics of Cu(In,Ga)Se2-based solar cells. Wediscuss deep defect levels derived from admittance and deep level transient spectroscopy, as well as shallowlevels affecting the charge distributions by capacitance–voltage profiling. The discussion includes two typesof metastable effects affecting capacitance characteristics: one induced at room temperature by light orvoltage bias, and one created at low temperature by red illumination of reverse-biased junction (ROB effect).Recent theoretical achievements on negative-U properties of such intrinsic defects as selenium vacancies andInCu antisites are used to explain the experimental data. We show that the most prominent level in theadmittance spectra is due to the response of interface states combined with contribution of deep VSe–VCu−/2−acceptor level. We attribute the ROB metastability to the relaxation of InCu defects upon electron capture.Finally we discuss the influence of these defects on the device efficiency.
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5.
  • Larsson, Fredrik, et al. (författare)
  • Evaluation of different intrinsic ZnO and transparent conducting oxide layer combinations in Cu(In,Ga)Se2 solar cells
  • 2017
  • Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 633, s. 235-238
  • Tidskriftsartikel (refereegranskat)abstract
    • We studied the interaction of four different window layer combinations in Cu(In,Ga)Se-2 solar cells. Intrinsic ZnO (i-ZnO) layers were grown on CdS by either chemical vapor deposition (CVD) or magnetron sputtering. These were combined with sputtered ZnO:Al or In2O3:H grown by atomic layer deposition as transparent conducting oxides (TCO). It was found that the thickness of the CVD i-ZnO layer affects the open circuit voltage (V-oc) significantly when using In2O3:H as TCO. The V-oc dropped by roughly 30 mV when the i-ZnO thickness was increased from 20 to 160 nm. This detrimental effect on V-oc was not as prominent when a ZnO:Al TCO was used, where the corresponding decrease was in the range of 5 to 10 my. In addition, the V-oc drop for the CVD i-ZnO/In2O3:H structure was not observed when using the sputtered i-ZnO layer. Furthermore, large fill factor variations were observed when using the In2O3:H TCO without an i-ZnO layer underneath, where already a thin (20 nm) CVD i-ZnO layer mitigated this effect. Device simulations were applied to explain the experimentally observed Voc trends.
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6.
  • Ledinek, Dorothea, et al. (författare)
  • Effect of NaF pre-cursor on alumina and hafnia rear contact passivation layers in ultra-thin Cu(In,Ga)Se2 solar cells
  • 2019
  • Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 683, s. 156-164
  • Tidskriftsartikel (refereegranskat)abstract
    • In this work, we evaluate the effect of NaF layers on the properties of Al2O3 and HfO2 rear contact passivation layers in ultra-thin Cu(In,Ga)Se2 solar cells. The 6 nm thin passivation layers were deposited by atomic layer deposition and neither intentionally opened nor nano-patterned in any extra-fabrication step. NaF layers, 7.5 or 15 nm thin, were deposited as precursors prior to CIGS absorber co-evaporation. The 215 nm thick absorbers were co-evaporated with constant evaporation rates for all elements. Directly thereafter, a 70 nm thick cadmium sulfide layer was deposited. Photoluminescence measurements indicate a strongly reduced recombination at the rear contact for all passivated samples compared to an unpassivated reference. Although the sample with Al2O3 passivation and a 15 nm NaF precursor layer luminesces by far the least of the passivated samples, solar cells made from this sample show the highest efficiency (8.6% compared with 5.6% for the reference with no passivation). The current-voltage curves of the solar cells fabricated from the sample with 7.5 nm NaF on top of the Al2O3 layer and both samples with HfO2 exhibit blocking behavior to various degrees, but a high photoluminescence response. We conclude that NaF precursor layers increase conduction through the Al2O3 layer, but also reduce its effectiveness as a passivation layer. In contrast, conduction through the HfO2 passivation layers seem to not be influenced by NaF precursor layers, and thus requires nano-patterning or thinning for conduction.
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7.
  • Lindahl, Johan, 1984-, et al. (författare)
  • The effect of substrate temperature on atomic layer deposited zinc tin oxide
  • 2015
  • Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 586, s. 82-87
  • Tidskriftsartikel (refereegranskat)abstract
    • Zinc tin oxide (ZTO) thin films were deposited on glass substrates by atomic layer deposition (ALD), and the film properties were investigated for varying deposition temperatures in the range of 90 to 180 degrees C. It was found that the [Sn]/([Sn] + [Zn]) composition is only slightly temperature dependent, while properties such as growth rate, film density, material structure and band gap are more strongly affected. The growth rate dependence on deposition temperature varies with the relative number of zinc or tin containing precursor pulses and it correlates with the growth rate behavior of pure ZnO and SnOx ALD. In contrast to the pure ZnO phase, the density of the mixed ZTO films is found to depend on the deposition temperature and it increases linearly with about 1 g/cm(3) in total over the investigated range. Characterization by transmission electron microscopy suggests that zinc rich ZTO films contain small (similar to 10 nm) ZnO or ZnO(Sn) crystallites embedded in an amorphous matrix, and that these crystallites increase in size with increasing zinc content and deposition temperature. These crystallites are small enough for quantum confinement effects to reduce the optical band gap of the ZTO films as they grow in size with increasing deposition temperature.
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8.
  • Szaniawski, Piotr, et al. (författare)
  • Light-enhanced reverse breakdown in Cu(In,Ga)Se2 solar cells
  • 2013
  • Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 535, s. 326-330
  • Tidskriftsartikel (refereegranskat)abstract
    • Partial shading of solar modules can subject shaded cells to significant reverse bias, often large enough toforce them into electrical breakdown, possibly resulting in irreversible damage. Therefore, better understandingof reverse current–voltage characteristics might lead to improvements in the design of solar modules. Thefocus of this study is the breakdown behavior of Cu(In,Ga)Se2 (CIGS) cells in darkness and under illumination.Two series of CIGS cells were investigated, with CdS and Zn–Sn–O buffer layers of varying thickness. Electricalbreakdown was found to be highly dependent on the buffer layer. Under blue illumination a remarkable decreasein breakdown voltage was observed for both buffer types. Metastable defects in the buffer/CIGS interfaceregion are tentatively proposed as the source of this effect and tunnelling is suggested as the mainmechanism responsible for breakdowns.
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  • Resultat 1-8 av 8

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