| 1. |
- Abedin, Ahmad, et al.
(författare)
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Sensitivity of the crystal quality of SiGe layers grown at low temperatures by trisilane and germane
- 2016
-
Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 613, s. 38-42
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Tidskriftsartikel (refereegranskat)abstract
- This work investigates the crystal quality of SiGe layers grown at low temperatures using trisilane, and germane precursors. The crystal quality sensitivity was monitored for hydrogen chloride and/or minor oxygen amount during SiGe epitaxy or at the interface of SiGe/Si layers. The quality of the epi-layerswas examined by quantifying noise parameter, K-1/f obtained from the power spectral density vs. 1/f curves. The results indicate that while it is difficult to detect small defect densities in SiGe layers by physical material characterization, the noise measurement could reveal the effects of oxygen contamination as low as 0.16mPa inside and in the interface of the layers.
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| 2. |
- Abou-Ras, Daniel, et al.
(författare)
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Innovation highway : Breakthrough milestones and key developments in chalcopyrite photovoltaics from a retrospective viewpoint
- 2017
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 633, s. 2-12
-
Tidskriftsartikel (refereegranskat)abstract
- The present contribution is a summary of an event that was organized as a special evening session in Symposium V "Chalcogenide Thin-Film Solar Cells" at the E-MRS 2016 Spring Meeting, Lille, France. The presentations in this session were given by the coauthors of this paper. These authors present retrospectives of key developments in the field of Cu(In,Ga)(S,Se)(2) solar cells as they themselves had witnessed in their laboratories or companies. Also, anecdotes are brought up, which captured interesting circumstances in that evolutionary phase of the field. Because the focus was on historical perspectives rather than a comprehensive review of the field, recent developments intentionally were not addressed.
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| 3. |
- Agnarsson, Björn, 1977, et al.
(författare)
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Rutile TiO 2 thin films grown by reactive high power impulse magnetron sputtering
- 2013
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 545, s. 445-450
-
Tidskriftsartikel (refereegranskat)abstract
- Thin TiO 2 films were grown on Si(001) substrates by reactive dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS) at temperatures ranging from 300 to 700 C.Optical and structural properties of films were compared both before and after post-annealing using scanning electron microscopy, low angle X-ray reflection (XRR), grazing inc idence X-ray diffractometry and spectroscopic ellipsometry.Both dcMS- and HiPIMS-grown films reveal polycrystalline rutile TiO 2 , even prior to post-annealing.The HiPIMS-grown films exhibit significantly larger grains compared to that of dcMC-grown films, approaching 100% of the film thickness for films grown at 700 C.In addition, the XRR surface roughness of HiPIMS-grown films was significantly lower than that of dcMS-grown films over the whole temperature range 300-700 C.Dispersion curves could only be obtained for the HiPIMS-grown films, which were shown to have a refractive index in the range of 2.7-2.85 at 500 nm.The results show that thin, rutile TiO 2 films, with high refractive index, can be obtained by HiPIMS at relatively low growth temperatures, without post-annealing.Furthermore, these films are smoother and show better optical characteristics than their dcMS-grown counterparts.© 2013 Elsevier B.V.All rights reserved.
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| 4. |
- Agnarsson, Björn, et al.
(författare)
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The effect of hard nitridation on Al(2)O(3) using a radio frequency operated plasma cell
- 2011
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 519:22, s. 7796-7802
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Tidskriftsartikel (refereegranskat)abstract
- We report on an atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) investigation of hard nitridation of sapphire (alpha.-Al(2)O(3)) substrate, using an Epi UNI-Bulb RF plasma cell at substrate temperatures ranging from 250 to 600 degrees C. Our results show that an AlN(1-x)O(x) layer forms on sapphire after extended nitridation at all temperatures, following a Stranski-Krastanov growth mode, with less islands forming at higher temperatures. We also observe a layer-dependent charging shift in XPS, separating smooth AlN(1-x)O(x) layers from rough AlN(1-x)O(x) islands due to their different electronic coupling to the substrate. Although the island growth is suppressed at higher temperatures, the surface roughness increases at higher temperatures as seen by AFM. We also observe sputtering effects with protrusions and pits.
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| 5. |
- Aiempanakit, Montri, et al.
(författare)
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Hysteresis and process stability in reactive high power impulse magnetron sputtering of metal oxides
- 2011
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 519:22, s. 7779-7784
-
Tidskriftsartikel (refereegranskat)abstract
- In the further development of reactive sputter deposition, strategies which allow for stabilization of the transition zone between the metallic and compound modes, elimination of the process hysteresis, and increase of the deposition rate, are of particular interest. In this study, the hysteresis behavior and the characteristics of the transition zone during reactive high power impulse magnetron sputtering (HiPIMS) of Al and Ce targets in an Ar-O(2) atmosphere as a function of the pulsing frequency and the pumping speed are investigated. Comparison with reactive direct current magnetron sputtering (DCMS) reveals that HiPIMS allows for elimination/suppression of the hysteresis and a smoother transition from the metallic to the compound sputtering mode. For the experimental conditions employed in the present study, optimum behavior with respect to the hysteresis width is obtained at frequency values between 2 and 4 kHz, while HiPIMS processes with values below or above this range resemble the DCMS behavior. Al-O films are deposited using both HiPIMS and DCMS. Analysis of the film properties shows that elimination/suppression of the hysteresis in HiPIMS facilitates the growth of stoichiometric and transparent Al(2)O(3) at relatively high deposition rates over a wider range of experimental conditions as compared to DCMS.
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| 6. |
- Alvi, Sajid Ali, et al.
(författare)
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Adaptive nanolaminate coating by atomic layer deposition
- 2019
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Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 692
-
Tidskriftsartikel (refereegranskat)abstract
- Atomic layer deposition (ALD) was used to deposit ZnO/Al2O3/V2O5 nanolaminate coatings to demonstrate a coating system with temperature adaptive frictional behaviour. The nanolaminate coating exhibited excellent conformity and crack-free coating of thickness 110 nm over Inconel 718 substrate. The ALD trilayer coating showed a hardness and elastic modulus of 12 GPa and 193 GPa, respectively. High-temperature tribology of the nanolaminate trilayer was tested against steel ball in dry sliding condition at 25 °C (room temperature, RT), 200 °C, 300 °C, and 400 °C. It was found that the nanolaminate coating showed a low coefficient of friction (COF) and wear rate at RT and 300 °C. The trilayer coating was found intact and stable at all temperatures during the friction tests. The adaptability of nanolaminate coating with the temperature was verified by performing the cyclic friction test at 300 °C and RT. The low COF and wear rate had been attributed to the (100) and (002) basal plane sliding of ZnO top layer, and the interlayer sliding of weakly bonded planes parallel to (001) plane in V2O5 bottom layer. Furthermore, even after the removal of ZnO coating during the tribotest, the bottom V2O5 layer coating stabilized the COF and wear rate at RT and 300 °C.
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| 7. |
- Anders, Andre, et al.
(författare)
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High quality ZnO:Al transparent conducting oxide films synthesized by pulsed filtered cathodic arc deposition
- 2010
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 518:12, s. 3313-3319
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Tidskriftsartikel (refereegranskat)abstract
- Aluminum-doped zinc oxide, ZnO:Al or AZO, is a well-known n-type transparent conducting oxide with great potential in a number of applications currently dominated by indium tin oxide. In this study, the optical and electrical properties of AZO thin films deposited on glass and silicon by pulsed filtered cathodic arc deposition are systematically studied. In contrast to magnetron sputtering, this technique does not produce energetic negative ions, and therefore ion damage can be minimized. The quality of the AZO films strongly depends on growth temperature while only marginal improvements are obtained with post-deposition annealing. The best films, grown at a temperature of about 200 degrees C, have resistivities in the low to mid 10(-4) Omega cm range with a transmittance better than 85% in the visible part of the spectrum. It is remarkable that relatively good films of small thickness (60 nm) can be fabricated using this method.
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| 8. |
- Andersson, Matilda, et al.
(författare)
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Magnetron sputtering of Zr-Si-C thin films
- 2012
-
Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 520:20, s. 6375-6381
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Tidskriftsartikel (refereegranskat)abstract
- The phase composition and chemical bonding of Zr-C and Zr-Si-C films deposited by magnetron sputtering has been studied. The results show that the binary Zr-C films at higher carbon contents form nanocrystallites of ZrC in an amorphous carbon matrix. The addition of Si induces a complete amorphization of the films above a critical concentration of about 15 at.%. X-ray diffraction and transmission electron microscopy confirm that the amorphous films contain no nanocrystallites and therefore can be described as truly amorphous carbides. The amorphous films are thermally stable but start to crystallize above 500 degrees C. Analysis of the chemical bonding with X-ray photoelectron spectroscopy suggests that the amorphous films exhibit a mixture of different chemical bonds such as Zr-C, Zr-Si and Si-C and that the electrical and mechanical properties are dependent on the distribution of these bonds. For higher carbon contents, strong Si-C bonds are formed in the amorphous Zr-Si-C films making them harder than the corresponding binary Zr-C films.
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| 9. |
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| 10. |
- Aouadi, S, et al.
(författare)
-
ICMCTF 2014 : Preface
- 2014
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Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 572, s. 1-1
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Tidskriftsartikel (refereegranskat)abstract
- The 41st International Conference on Metallurgical Coatings andThin Films (ICMCTF), sponsored by the Advanced Surface EngineeringDivision (ASED) of the American Vacuum Society (AVS), was heldfrom April 28 to May 2, 2014 in San Diego, California, USA.The week's technical program consisted of 37 technical sessions,which were organized into 13 symposia. The conference opened witha Plenary Lecture by Prof. Sybrand van der Zwaag, Materials Scienceand Engineering at the faculty of Aerospace Engineering at the TUDelft, The Netherlands, on “Self-healing Materials: an Alternative Approachto Create More Durable/Reliable Materials and Products”. TheExhibition Keynote Lecture was presented by Prof. Timothy P. Weihs,Department of Materials Science and Engineering at the Johns HopkinsUniversity, Baltimore, MD, USA, on “Driving Commercial Applicationsand Exploring Scientific Questions with Reactive Multilayer Foils”.During the conference week, a well subscribed poster session wasattended by a large and appreciative attendee audience. An expansivelarge two-day interactive industrial exhibition, with more than 50booths,was held inwhich companies displayed theirmost recent developmentsin vacuumscience and plasma-based deposition technologies.In addition to the technical symposia sessions, there were threefocused topical sessions, and six specialized short courses offered.Professor Jindrich Musil from the faculty of Applied Sciences atthe University of Bohemia, Plzeň, Czech Republic, was the recipientof the 2014 ASED R.F. Bunshah Annual Award; he presented the HonoraryLecture, “Advanced Hard Nanocomposite Coatings with UniqueProperties”. The award recognizes and honors Prof. Musil's seminalcontributions to the development of advanced nanocomposite coatingswith enhanced hardness, oxidation resistance, toughness, and crackresistance.The ASED Annual ICMCTF Graduate Student Awards werepresented to Shiyu Liu (Gold Medal), University of Cambridge, UK;Samantha K. Lawrence (Silver Medal), Purdue University, WestLafayette, IN, USA; and Trevor Hardcastle (Bronze Medal), Universityof Leeds, UK.The electronic submission and handling of manuscripts via theElsevier Editorial System (EES), including the selection of reviewersand evaluation ofmanuscripts,were identical to the procedures appliedto manuscripts submitted as regular contributions for publication ininternational scientific journals. Following the tradition practiced since1987, the accepted manuscripts are published in the archival journalsSurface and Coatings Technology and Thin Solid Films. ICMCTF 2014proceedings are open-access to the participants for one year via theElsevier journals' web sites.The organization of this conference and the preparation of proceedingsvolumes would have been impossible without the tremendouseffort and dedication of many individuals, including the General Chair,Yip-Wah Chung, Northwestern University, USA, and the ProgramChair, Claus Rebholz, the University of Cyprus, the team of symposiaand session chairs that made possible the realization of an exciting technicalprogram. We especially thank all the authors and presenters fortheir contributions; we also thank the hundreds of reviewers for theirtimely submission of high quality reports. To our sponsors,we acknowledge,appreciate, and thank these companies for their most generousand continuing support.The 42nd International Conference on Metallurgical Coatings andThin Films (ICMCTF 2015) will be held in San Diego, California, April20–24, 2015, with Claus Rebholz, University of Cyprus, as the GeneralChair and Suneel Kodambaka, the University of California at Los Angeles, as the Program Chair.
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| 11. |
- Aouadi, Samir, et al.
(författare)
-
ICMCTF 2017-Preface
- 2017
-
Ingår i: Thin Solid Films. - : ELSEVIER SCIENCE SA. - 0040-6090 .- 1879-2731. ; 644
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
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| 12. |
- Arvizu, Miguel A, et al.
(författare)
-
Electrochemical pretreatment of electrochromic WO3 films gives greatly improved cycling durability
- 2018
-
Ingår i: Thin Solid Films. - : ELSEVIER SCIENCE SA. - 0040-6090 .- 1879-2731. ; 653, s. 1-3
-
Tidskriftsartikel (refereegranskat)abstract
- Electrochromic WO3 thin films have important applications in devices such as smart windows for energy-efficient buildings. Long-term electrochemical cycling durability of these films is essential and challenging. Here we investigate reactively sputter-deposited WO3 films, backed by indium-tin oxide layers and immersed in electrolytes of LiClO4 in propylene carbonate, and demonstrate unprecedented electrochemical cycling durability after straight-forward electrochemical pretreatments by the application of a voltage of 6 V vs. Li/Li+ for several hours.
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| 13. |
- Arwin, Hans, 1950-, et al.
(författare)
-
Comparison and analysis of Mueller-matrix spectra from exoskeletons of blue, green and red Cetonia aurata
- 2014
-
Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 571, s. 739-743
-
Tidskriftsartikel (refereegranskat)abstract
- The exoskeleton, also called the cuticle, of specimens of the scarab beetle Cetonia aurata is a narrow-band reflector which exhibits metallic shine. Most specimens of C. aurata have a reflectance maximum in the green part of the spectrum but variations from blue–green to red–green are also found. A few specimens are also more distinct blue or red. Furthermore, the reflected light is highly polarized and at near-normal incidence near-circular left-handed polarization is observed. The polarization and color phenomena are caused by a nanostructure in the cuticle. This nanostructure can be modeled as a multilayered twisted biaxial layer from which reflection properties can be calculated. Specifically we calculate the cuticle Mueller matrix which then is fitted to Mueller matrices determined by dual-rotating compensator ellipsometry in the spectral range 400–800 nm at multiple angles of incidence. This non-linear regression analysis provides structural parameters like pitch of the chiral structure as well as layer refractive index data for the different layers in the cuticle. The objective here is to compare spectra measured on C. aurata with different colors and develop a generic structural model. Generally the degree of polarization is large in the spectral region corresponding to the color of the cuticle which for the blue specimen is 400–600 nm whereas for the red specimen it is 530–730 nm. In these spectral ranges, the Mueller-matrix element m41 is non-zero and negative, in particular for small angles of incidence, implicating that the reflected light becomes near-circularly polarizedwith an ellipticity angle in the range 20°–45°.
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| 14. |
- Azarov, Alexander, et al.
(författare)
-
Dopant incorporation in thin strained Si layers implanted with Sb
- 2010
-
Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 518:9, s. 2474-2477
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of tensile strain on Sb incorporation in Si and its activation during post-implantation annealing has been Studied by a combination of Rutherford backscattering/channeling spectrometry, secondary ion mass spectrometry. X-ray diffraction and 4-point probe measurements Our results show that, for Sb implanted samples a tensile strain has an important role for dopant behavior Particularly, increasing the tensile strain in the Si layer from 0 to 0 8% leads to an enhancement of the fraction of incorporated Sb atoms in substitutional sites already during implantation from similar to 7 to 30% Furthermore, 0 8% strain in antimony doped Si gives similar to 20% reduction in the sheet resistance in comparison to the unstrained sample.
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| 15. |
- Barbe, Jeremy, et al.
(författare)
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Silicon nanocrystals on amorphous silicon carbide alloy thin films : Control of film properties and nanocrystals growth
- 2012
-
Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 522, s. 136-144
-
Tidskriftsartikel (refereegranskat)abstract
- The present study demonstrates the growth of silicon nanocrystals on amorphous silicon carbide alloy thin films. Amorphous silicon carbide films [a-Si1 − xCx:H (with x < 0.3)] were obtained by plasma enhanced chemical vapor deposition from a mixture of silane and methane diluted in hydrogen. The effect of varying the precursor gas-flow ratio on the film properties was investigated. In particular, a wide optical band gap (2.3 eV) was reached by using a high methane-to-silane flow ratio during the deposition of the a-Si1 − xCx:H layer. The effect of short-time annealing at 700 °C on the composition and properties of the layer was studied by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. It was observed that the silicon-to-carbon ratio in the layer remains unchanged after short-time annealing, but the reorganization of the film due to a large dehydrogenation leads to a higher density of SiC bonds. Moreover, the film remains amorphous after the performed short-time annealing. In a second part, it was shown that a high density (1 × 1012 cm− 2) of silicon nanocrystals can be grown by low pressure chemical vapor deposition on a-Si0.8C0.2 surfaces at 700 °C, from silane diluted in hydrogen. The influence of growth time and silane partial pressure on nanocrystals size and density was studied. It was also found that amorphous silicon carbide surfaces enhance silicon nanocrystal nucleation with respect to SiO2, due to the differences in surface chemical properties.
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| 16. |
- Bárdos, Ladislav, et al.
(författare)
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Cold atmospheric plasma : Sources, processes, and applications
- 2010
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 518:23, s. 6705-6713
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Tidskriftsartikel (refereegranskat)abstract
- Atmospheric pressure gas discharge plasmas, especially those operated at energy non-equilibrium and low gas temperatures, have recently become a subject of great interest for a wide variety of technologies including surface treatment and thin-film deposition. A driving force for these developments is the avoidance of expensive equipment required for competing vacuum-based plasma technologies. Although there are many applications where non-equilibrium (cold) plasma at atmospheric and higher pressures represents a substantial advantage, there are also a number of applications where low-pressure plasmas simply cannot be replaced due to specific properties and limitations of the atmospheric plasma and related equipment. In this critical review, the primary principles and characteristics of the cold atmospheric plasma and differences from vacuum-based plasma processes are described and discussed to provide a better understanding of the capabilities and limits of emerging atmospheric plasma technologies.
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| 17. |
- Bastuck, Manuel, et al.
(författare)
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Exploring the selectivity of WO3 with iridium catalyst in an ethanol/naphthalene mixture using multivariate statistics
- 2016
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Ingår i: Thin Solid Films. - : ELSEVIER SCIENCE SA. - 0040-6090 .- 1879-2731. ; 618, s. 263-270
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Tidskriftsartikel (refereegranskat)abstract
- Temperature cycled operation and multivariate statistics have been used to compare the selectivity of two gate (i.e. sensitive) materials for gas-sensitive, silicon carbide based field effect transistors towards naphthalene and ethanol in different mixtures of the two substances. Both gates have a silicon dioxide (SiO2) insulation layer and a porous iridium (Ir) electrode. One of it has also a dense tungsten trioxide (WO3) interlayer between Ir and SiO2. Both static and transient characteristics play an important role and can contribute to improve the sensitivity and selectivity of the gas sensor. The Ir/SiO2 is strongly influenced by changes in ethanol concentration, and is, thus, able to quantify ethanol in a range between 0 and 5 ppm with a precision of 500 ppb, independently of the naphthalene concentrations applied in this investigation. On the other hand, this sensitivity to ethanol reduces its selectivity towards naphthalene, whereas Ir/WO3/SiO2 shows an almost binary response to ethanol. Hence, the latter has a better selectivity towards naphthalene and can quantify legally relevant concentrations down to 5 ppb with a precision of 2.5 ppb, independently of a changing ethanol background between 0 and 5 ppm. (C) 2016 Elsevier B.V. All rights reserved.
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| 18. |
- Berg, Sören, et al.
(författare)
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Upgrading the “Berg-model” for reactive sputtering processes
- 2014
-
Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 565, s. 186-192
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Forskningsöversikt (refereegranskat)abstract
- Several phenomena are neglected in the original “Berg model” in order to provide a simple model of the reactive sputtering process. There exist situations, however, where this simplified treatment limits the usefulness of the model. To partly correct for this, we introduce an upgraded version of the basic model. We abandon the simplifying assumption that compound targets are sputter eroded as molecules. Instead, the molecule is split and individual atoms will be sputter ejected. Also, the effect of ionized reactive gas atoms implanted into the target will be considered. We outline how to modify the original model to include these effects. Still, the mathematical treatment is maintained simple so that the new model may serve as an easy-to-understand tutorial of the complex mechanisms of reactive sputtering.
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| 19. |
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| 20. |
- Borges, J., et al.
(författare)
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Microstructural evolution of Au/TiO2 nanocomposite films : The influence of Au concentration and thermal annealing
- 2015
-
Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 580, s. 77-88
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Tidskriftsartikel (refereegranskat)abstract
- Nanocomposite thin films consisting of a dielectric matrix, such as titanium oxide (TiO2), with embedded gold (Au) nanoparticles were prepared and will be analysed and discussed in detail in the present work. The evolution of morphological and structural features was studied for a wide range of Au concentrations and for annealing treatments in air, for temperatures ranging from 200 to 800 degrees C. Major findings revealed that for low Au atomic concentrations (at.%), there are only traces of clustering, and just for relatively high annealing temperatures, T >= 500 degrees C. Furthermore, the number of Au nanoparticles is extremely low, even for the highest annealing temperature, T = 800 degrees C. It is noteworthy that the TiO2 matrix also crystallizes in the anatase phase for annealing temperatures above 300 degrees C. For intermediate Au contents (5 at.% <= C-Au <= 15 at.%), the formation of gold nanoclusters was much more evident, beginning at lower annealing temperatures (T >= 200 degrees C) with sizes ranging from 2 to 25 nm as the temperature increased. A change in the matrix crystallization from anatase to rutile was also observed in this intermediate range of compositions. For the highest Au concentrations (>20 at.%), the films tended to form relatively larger clusters, with sizes above 20 nm (for T >= 400 degrees C). It is demonstrated that the structural and morphological characteristics of the films are strongly affected by the annealing temperature, as well as by the particular amounts, size and distribution of the Au nanoparticles dispersed in the TiO2 matrix.
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| 21. |
- Borges, J., et al.
(författare)
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Thin films composed of gold nanoparticles dispersed in a dielectric matrix : The influence of the host matrix on the optical and mechanical responses
- 2015
-
Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 596, s. 8-17
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Tidskriftsartikel (refereegranskat)abstract
- Gold nanoparticles were dispersed in two different dielectric matrices, TiO2 and Al2O3, using magnetron sputtering and a post-deposition annealing treatment. The main goal of the present work was to study how the two different host dielectric matrices, and the resulting microstructure evolution (including both the nanoparticles and the host matrix itself) promoted by thermal annealing, influenced the physical properties of the films. In particular, the structure and morphology of the nanocomposites were correlated with the optical response of the thin films, namely their localized surface plasmon resonance (LSPR) characteristics. Furthermore, and in order to scan the future application of the two thin film system in different types of sensors (namely biological ones), their functional behaviour (hardness and Young's modulus change) was also evaluated. Despite the similar Au concentrations in both matrices (similar to 11 at.%), very different microstructural features were observed, which were found to depend strongly on the annealing temperature. The main structural differences included: (i) the early crystallization of the TiO2 host matrix, while the Al2O3 one remained amorphous up to 800 degrees C; (ii) different grain size evolution behaviours with the annealing temperature, namely an almost linear increase for the Au:TiO2 system (from 3 to 11 nm), and the approximately constant values observed in the Au:Al2O3 system (4-5 nm). The results from the nanoparticle size distributions were also found to be quite sensitive to the surrounding matrix, suggesting different mechanisms for the nanoparticle growth (particle migration and coalescence dominating in TiO2 and Ostwald ripening in Al2O3). These different clustering behaviours induced different transmittance-LSPR responses and a good mechanical stability, which opens the possibility for future use of these nanocomposite thin film systems in some envisaged applications (e.g. LSPR-biosensors).
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| 22. |
- Bose, Sourav, et al.
(författare)
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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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| 23. |
- Bras, Patrice, et al.
(författare)
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Ga-grading and Solar Cell Capacitance Simulation of an industrial Cu(In,Ga)Se2 solar cell produced by an in-line vacuum, all-sputtering process
- 2017
-
Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 636, s. 367-374
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Tidskriftsartikel (refereegranskat)abstract
- Cadmium-free Cu(In,Ga)Se-2 (CIGS) solar cells are fabricated on stainless steel substrate using an industrial, inline vacuum, all sputtering process. The absorber layer is deposited from compound CIGS targets and crystallized simultaneously by high temperature processing. In-depth compositional and structural characterization of the chalcopyrite material is conducted and a Solar Cell Capacitance Simulator (SCAPS) model for the complete device is set-up. Ga-grading of the absorber through the successive use of different CIGS target compositions and resulting in solar cell performance enhancement is shown. At the research and development scale, efficiency values of 15.1% and 13.2% are reported for 1 cm(2) and 225 cm(2) total area solar cells, respectively. Successful transfer to production is also demonstrated. A series of a hundred 225 cm(2) solar cells produced following an optimized process including the Ga grading studied in the present contribution average at 14.8% total area efficiency.
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| 24. |
- Bras, Patrice, et al.
(författare)
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Influence of hydrogen sulfide annealing on copper-zinc-tin-sulfide solar cells sputtered from a quaternary compound target
- 2015
-
Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 582, s. 233-238
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Tidskriftsartikel (refereegranskat)abstract
- With a theoretical efficiency around 30% and an optimized band gap for sunlight absorption, Cu2ZnSnS4 (CZTS) is a promising, earth-abundant, material for thin film solar cells. Sputtering CZTS from a quaternary compound target is a quick and potentially industrial-scaled process that has not been investigated deeply yet. Our approach is based on an in-line vacuum system for the complete device. CZTS is sputtered from a compound target on a sodium molybdate (MoNa) pre-sputtered stainless steel substrate, and then annealed in high-pressure H2S atmosphere. A 1 mu m thick absorber is obtained within 7 minute sputtering. Top layers are then deposited, without vacuum breaking. The effects of different annealing temperatures on the absorber morphology and composition are investigated. It is observed that recrystallization already occurs at 420 degrees C and that crystallinity improves with increasing temperature up to 550 degrees C. However, micro-sphere formation underneath the film degrades the corresponding solar cell performance dramatically above 510 degrees C. It is shown that sodium is needed in order to enhance recrystallization of CZTS but the MoNa layer thickness seems not to be a critical parameter. Scanning electron microscopy, X-ray diffraction, X-ray fluorescence and current-voltage measurement were used to characterize the samples.
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| 25. |
- Brobbey, Kofi, et al.
(författare)
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Effect of plasma coating on antibacterial activity of silver nanoparticles
- 2019
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 672, s. 75-82
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Tidskriftsartikel (refereegranskat)abstract
- Silver nanoparticles (NPs) are known to provide antimicrobial properties for surfaces. However, there are environmental concerns due to reports of toxicity after exposure to the environment during or after end-use. Immobilizing silver NPs to the surface of substrates could ensure that particles are readily available for antibacterial activity with limited environmental exposure. A plasma coating on top of silver NPs could improve the adhesion of NPs to a substrate, but it could also impede the release of silver NPs completely. Furthermore, silver has been shown to require direct contact to demonstrate antibacterial activity. This study demonstrates immobilization of silver NPs with plasma coating onto a surface while maintaining its antibacterial properties. Silver NPs are simultaneously synthesized and deposited onto a surface with liquid flame spray aerosol technique followed by hexamethyldisiloxane plasma coating to immobilize the NPs. Atomic force microscope scratch testing is used to demonstrate improved nanoparticle adhesion. Antibacterial activity against gram-negative Escherichia coli is maintained even for plasma coating thicknesses of 195 nm. NP adhesion to the surface is significantly improved. Gram-positive Staphylococcus aureus was found be resistant to all the plasma-coated samples. The results show promise of using plasma coating technology for limiting NP exposure to environment.
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