| 1. |
- Benatto, L., et al.
(författare)
-
Comparing C-60 and C-70 as acceptor in organic solar cells : Influence of the electronic structure and aggregation size on the photovoltaic characteristics
- 2020
-
Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 697
-
Tidskriftsartikel (refereegranskat)abstract
- The difference in aggregation size of the C-60 and C-70 fullerenes affect the photovoltaic performance of devices assembled in the so-called bilayer architecture with poly [2,7-(9,9- dioctyl- dibenzosilole)- alt-4,7- bis(thiophen-2-yl)benzo- 2,1,3- thiadiazole] (PSiF-DBT) as the electron donor material. Despite the better performance of the C-70 devices, which is related to the high absorption coefficient in the visible range and the superior charge transport properties, the short-circuit current variation upon annealing treatment at 100 degrees C is approximately twice bigger when the C-60 is the acceptor. We attribute this effect to the tendency of C-60 in form smaller aggregate domains relatively to the C-70. The increased roughness on the polymeric surface after annealing results in an enhanced donor/acceptor contact area and assists the fullerene diffusion deeper inside the polymeric layer. This effect leads to a better mixing between donor and acceptor species and create a interpenetrating layer close to the so-called bulk heterojunction. Since C-60 forms smaller aggregates, this mechanism is more pronounced for this molecule. Therefore, a significant variation in the performance of the C-60 devices is observed after this kind of treatment. Density Functional Theory calculations of the potential energy of interaction between two fullerene molecules and X-Ray measurements gives evidences to support this idea. In addition, combining spectrally resolved external quantum efficiency measurements with optical modeling our results also indicate the occurrence of the bilayer interfacial mixing for PSiF-DBT/C-60.
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| 2. |
- Crespi, Ângela Elisa, et al.
(författare)
-
Low resistivity amorphous carbon-based thin films employed as anti-reflective coatings on copper
- 2020
-
Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 712
-
Tidskriftsartikel (refereegranskat)abstract
- Amorphous carbon-based coatings deposited on copper substrates by magnetron sputtering at different target-to-substrate distances were investigated. Films deposited at short distances as 2 cm presented the best results in terms of morphology, density, and resistivity. Ultraviolet near-infrared range spectrometry measurements determined total reflectance and ellipsometry, extinction coefficient, refraction index, and pseudo bandgap. Amorphous carbon films of 150 nm deposited at 2 cm reduced the total reflectance by up to 60 ± 5% in the near-infra-red range when compared to pure copper films. The addition of Fe* boosts the absorption of the coating reducing the total reflectance by up to 70 ± 5% in near-infrared. (Fe*: deposited from stainless-steel target used in direct-current magnetron sputtering). Also, Fe* reduces the electrical resistivity by a factor of 100 compared to that of pure amorphous carbon films. The reduction in total reflectance induced by the presence of the amorphous carbon-based films on copper depends, as expected, on light penetration depth and the absorption coefficient.
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| 3. |
- Duy, Nguyen Van, et al.
(författare)
-
Enhancement of NH3 gas sensing with Ag-Pt co-catalyst on SnO2 nanofilm towards medical diagnosis
- 2023
-
Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 767
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Tidskriftsartikel (refereegranskat)abstract
- Exhaled breath analysis is a noninvasive diagnostic method for fatal disease monitoring and screening, which is recently gained extensive interest of researchers worldwide emphasizing on the development of effective chemiresistive gas sensor for practical application. Here, the Ag-Pt bimetallic nanoparticles were used to deco-rate nanofilms of SnO2 making different gas sensors with high performance. We found that the bimetal alloy improved the sensor performance significantly with super sensitivity as compared with the separate Ag and Pt catalyst. The right ratio of the bimetal made the sensor very sensitive to NH3, so that it was able to quickly (12 s) detect 1 parts-per-million of NH3 with a response of 4.31 at a temperature of 250 degrees C. The sensor limit of detection for NH3 was less than 10 parts-per-billion. The response of the sensor was negligibly affected by humidity and interfering gases. The results showed that the tiny, robust, and inexpensive sensor developed in this work can be used in breath analysis for early diagnosis via NH3 monitoring.
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| 4. |
- Edström, Helen, et al.
(författare)
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Alloying and Oxidation of PdAu Thin Films
- 2024
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Ingår i: Thin Solid Films. - 0040-6090. ; 790
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Tidskriftsartikel (refereegranskat)abstract
- The relation between catalytic activity and the presence of oxides on the catalyst’s surface has proven very complex, especially in the case of methane oxidation over Pd. While the metallic Pd surface and a thin, but at least two atomic layers thick, oxide film has been found catalytically active, a single-layer surface oxide or a too thick oxide film are both low-active. Unfortunately, under reaction conditions, the oxide tends to grow thick and deactivate. The reason for this deactivation is believed to be exposure of the PdO(100) surface, which does not have any suitable active sites for the methane adsorption and activation, in contrast to PdO(101), which is exposed for thin films. In an attempt to limit the thickness of the oxide film, and hence stabilise the active PdO orientation, we have investigated the oxidation of thin PdAu films. The effects of different mixtures (25%, 50%, and 75% Au, respectively) and treatments on the oxidation and orientation of the alloy and oxide films were investigated. As intended, PdAu turned out to be significantly more difficult to oxidise compared to pure Pd. This effect was even stronger than expected. Depending on the amount of Au present in the alloy, the orientation of the oxide is affected. At lower Au concentration, the desired (101) oxide orientation is favoured, while higher Au concentration favours the low-active (100) oxide orientation. Thus, PdAu might be a good candidate for methane oxidation if the Au concentration is low, probably below 25%. The larger lattice constant of Au compared to Pd might also affect the oxide orientation, so another choice of alloying material, e.g. PdPt, may also work to stabilise PdO(101).
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| 5. |
- Edström, Helen, et al.
(författare)
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Alloying and oxidation of PdAu thin films
- 2024
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Ingår i: Thin Solid Films. - 0040-6090. ; 790
-
Tidskriftsartikel (refereegranskat)abstract
- The relation between catalytic activity and the presence of oxides on the catalyst's surface has proven very complex, especially in the case of methane oxidation over Pd. While the metallic Pd surface and a thin, but at least two atomic layers thick, oxide film has been found catalytically active, a single-layer surface oxide or a too thick oxide film are both low-active. Unfortunately, under reaction conditions, the oxide tends to grow thick and deactivate. The reason for this deactivation is believed to be exposure of the PdO(100) surface, which does not have any suitable active sites for the methane adsorption and activation, in contrast to PdO(101), which is exposed for thin films. In an attempt to limit the thickness of the oxide film, and hence stabilise the active PdO orientation, we have investigated the oxidation of thin PdAu films. The effects of different mixtures (25%, 50%, and 75% Au, respectively) and treatments on the oxidation and orientation of the alloy and oxide films were investigated. As intended, PdAu turned out to be significantly more difficult to oxidise compared to pure Pd. This effect was even stronger than expected. Depending on the sample temperature and the amount of Au present in the alloy, the orientation of the oxide is affected. At lower temperatures and Au concentration, the desired [301] oxide orientation (corresponding to the (101) planes being parallel to the sample surface) is favoured, while higher Au concentration favours the low-active [100] oxide orientation. Thus, PdAu might be a good candidate for methane oxidation if the Au concentration is low, probably below 25%. The larger lattice constant of Au compared to Pd might also affect the oxide orientation, so another choice of alloying material, e.g. PdPt, may also work to stabilise PdO[301]. Independent of the alloy composition, the sample temperature during oxide growth should be optimised in order to achieve an active oxide film.
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| 6. |
- Geng, Dongsen, et al.
(författare)
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An investigation on microstructure and milling performance of arc-evaporated TiSin/AlTiN film
- 2020
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Ingår i: Thin Solid Films. - : ELSEVIER SCIENCE SA. - 0040-6090 .- 1879-2731. ; 709
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Tidskriftsartikel (refereegranskat)abstract
- In this work, TiSiN/AlTiN multilayer film was deposited on cemented-carbide solid end mill tools by cathodic arc evaporation. The multilayer consisted of CrN buffer layer, Al(0.6)7Ti(0.33)N adhesion layer, Ti0.9Si0.1N/Al(0.6)7Ti(0.33)N alternate layer, and Ti0.9Si0.1N outlayer. An investigation on microstructure, mechanical properties, high-temperature wear rate, and milling performance of TiSiN/AlTiN multilayer film was conducted. The results indicate that the as-deposited TiSiN/AlTiN film exhibits a mixture phase of fcc-TiN and fcc-(Ti, Al)N. The hardness and elastic modulus of the TiSiN/AlTiN film are 41.7 +/- 1.6 GPa and 340 +/- 17 GPa, respectively. The wear rate of TiSiN/AlTiN film changes slightly when the experiment temperature is below 400 degrees C, and then increases with the temperature increases to 600 degrees C. Indentation hardness of TiSiN/AlTiN changes can be maintained above 40 GPa upon annealing to 800 degrees C. However, the hardness of the film decreases from above 40 GPa to similar to 30.6 GPa when the annealing temperature increases to 1000 degrees C. During dry milling, the TiSiN/AlTiN film reduces the adhesion between the coated tool and machined material SKD 11, leading to a low cutting force and cutting temperature.
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| 7. |
- Grishin, Alexander M., et al.
(författare)
-
Optical dispersion and temperature dependent latching-type magneto-optical properties of magnetron sputtered Bi3Fe3.34Ga1.66O12 (001) and (111) films
- 2020
-
Ingår i: Thin Solid Films. - : ELSEVIER SCIENCE SA. - 0040-6090 .- 1879-2731. ; 699
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Tidskriftsartikel (refereegranskat)abstract
- We report on optical dispersion and temperature dependence of latching-type magneto-optical properties of heavily Ga-doped bismuth iron garnet films rf-magnetron sputtered onto Gd3Ga5O12 (001) and (111) substrates. At lambda = 677 nm and room temperature, epitaxial Bi3Fe3.34Ga1.66O12 (001) and (111) films show, respectively, saturation Faraday rotation theta(Fsat) = - 0.92 x 10(4) and - 1.05 x 10(4) deg/cm, transmittance T = 0.86 and 0.81, magnetic hysteresis theta(F)-H loop squareness theta(Frem)/theta(Fsat) = 0.84 and 1.0, and coercive field H-c = 6.76 and 24.03 kA/m. Film's Faraday rotation is nicely fitted by molecular field Neel theory in the whole temperature range from T-C = 316 K down to 85 K where theta(Fsat) = - 1.9 x 10(4) deg/cm and H-c = 151.20 kA/m.
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| 8. |
- Karlsson, Stefan, 1984-, et al.
(författare)
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Effects of deposition temperature on the mechanical and structural properties of amorphous Al-Si-O thin films prepared by radio frequency magnetron sputtering
- 2023
-
Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 787
-
Tidskriftsartikel (refereegranskat)abstract
- Aluminosilicate (Al–Si–O) thin films containing up to 31 at.% Al and 23 at.% Si were prepared by reactive RF magnetron co-sputtering. Mechanical and structural properties were measured by indentation and specular reflectance infrared spectroscopy at varying Si sputtering target power and substrate temperature in the range 100 to 500 °C. It was found that an increased substrate temperature and Al/Si ratio give denser structure and consequently higher hardness (7.4 to 9.5 GPa) and higher reduced elastic modulus (85 to 93 GPa) while at the same time lower crack resistance (2.6 to 0.9 N). The intensity of the infrared Si-O-Si/Al asymmetric stretching vibrations shows a linear dependence with respect to Al concentration. The Al–O–Al vibrational band (at 1050 cm−1) shifts towards higher wavenumbers with increasing Al concentration which indicates a decrease of the bond length, evidencing denser structure and higher residual stress, which is supported by the increased hardness. The same Al–O–Al vibrational band (at 1050 cm−1) shifts towards lower wavenumber with increasing substrate temperature indicating an increase in the average coordination number of Al.
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| 9. |
- Lemishko, S. V., et al.
(författare)
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Dielectric resonator in rectangular ??(102) cavity for electron paramagnetic resonance study of thin films
- 2023
-
Ingår i: Thin Solid Films. - : ELSEVIER SCIENCE SA. - 0040-6090 .- 1879-2731. ; 768
-
Tidskriftsartikel (refereegranskat)abstract
- The improved compared to a rectangular TE(102 )cavity geometry of a dielectric resonator (DR) suitable for studying thin films and coatings has been calculated and experimentally verified. It is shown that electron paramagnetic resonance (EPR) signal of SiOx films can be enhanced by using as the DR of two rectangular parallelepipeds fabricated from BaTi4O9 + 8.5% ZnO ceramics (epsilon=36) with dimension of 5.64x5.5 x 5.9 mm(3 )and a gap of up to 0.5 mm between them. Located inside a standard rectangular metal TE(102 )cavity of the X-band EPR spectrometer, the DR increases the filling factor by 5-12 times depending on the size of a sample studied. The experimental use of the DR allows to increase the EPR signal of the 950 nm SiOx thin film by a factor of approximately 4.
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| 10. |
- Levämäki, Henrik, et al.
(författare)
-
HADB: A materials-property database for hard-coating alloys
- 2023
-
Ingår i: Thin Solid Films. - : ELSEVIER SCIENCE SA. - 0040-6090 .- 1879-2731. ; 766
-
Tidskriftsartikel (refereegranskat)abstract
- Data-driven approaches are becoming increasingly valuable for modern science, and they are making their way into industrial research and development (R&D). Supervised machine learning of statistical models can utilize databases of materials parameters to speed up the exploration of candidate materials for experimental synthesis and characterization. In this paper we introduce the HADB database, which contains properties of industrially relevant chemically disordered hard-coating alloys, focusing on their thermodynamic, elastic and mechanical properties. We present the technical implementations of the database infrastructure including support for browse, query, retrieval, and API access through the OPTIMADE API to make this data findable, accessible, interoperable, and reusable (FAIR). Finally, we demonstrate the usefulness of the database by training a graph -based machine learning (ML) model to predict elastic properties of hard-coating alloys. The ML model is shown to predict bulk and shear moduli for out out-of-sample alloys with less than 6 GPa mean average error.
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| 11. |
- Linder, Clara, et al.
(författare)
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Effect of Mo content on the corrosion resistance of (CoCrFeNi)1−xMox thin films in sulfuric acid
- 2024
-
Ingår i: Thin Solid Films. - : Elsevier B.V.. - 0040-6090 .- 1879-2731. ; 790
-
Tidskriftsartikel (refereegranskat)abstract
- (CoCrFeNi)1−xMox thin films with various Mo content (0–10 at.%) were grown by magnetron sputtering on a stainless steel substrate. The films with 0–2 at.% presented two crystal structures: one FCC phase and one sigma phase, while films with higher Mo content only had the FCC structure. All films have a (111) texture and follow the topography of the substrate. The corrosion resistance of the films was evaluated in 0.05 M H2SO4 at room temperature and at 80 °C. It was observed that the corrosion current densities considerably decreased for Mo > 2 at%, and that the current densities were higher at the elevated temperature. Scanning Kelvin Probe Force Microscopy showed a large potential difference between the main FCC phase and sigma phase for the Mo0–2 films. This would suggest that preferential dissolution of the FCC phase occurs over the sigma and reduces the corrosion resistance. Such preferential dissolution does not occur for the higher Mo content films with only the FCC phase. The high corrosion resistance was also attributed to the inhibition of Fe and Cr dissolution by Mo and the stabilisation of the Cr enriched oxide by incorporating Mo oxides into the passive film, identified by X-ray photoelectron spectroscopy. The low corrosion current densities (below 1 µA/cm2) make these thin films possible candidates for protective coatings of bipolar plates in PEM fuel cells.
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| 12. |
- Mopoung, Kunpot, et al.
(författare)
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Investigation of in situ annealing effect on the thermal stability and crystallinity of IrMn thin films by X-ray diffraction and electron energy loss spectroscopy
- 2022
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Ingår i: Thin Solid Films. - : ELSEVIER SCIENCE SA. - 0040-6090 .- 1879-2731. ; 762
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Tidskriftsartikel (refereegranskat)abstract
- The crystal reorganization of the IrMn thin film was observed by the in situ thermal annealing in the X-ray diffraction (XRD) and electron energy loss spectroscopy. From room temperature to 700 degrees C, the in situ annealing measurements identify the different Mn diffusion effects in three temperature ranges. First, between room temperature and 300 degrees C, the XRD profiles show the reorganization of Mn atoms from interstitials to IrMn lattice points. Second, between 300 and 400 degrees C, we observed the diffusion of Mn atoms from the IrMn thin film to the surface, causing the atomic Mn/Ir ratio to drop from 10 to 7. The MnO appeared on the film surface in this temperature range. Third, from 400 to 700 degrees C, the O content in the IrMn thin film increases to 8%, while the Mn/ Ir ratio continuously decreases from 7 to 5. The scanning transmission electron microscopy images also show that the crystal structure of IrMn thin film completely degrades to another structure.
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| 13. |
- Nzulu, Gabriel Kofi, 1974-, et al.
(författare)
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Growth and thermal stability of Sc-doped BaZrO 3 thin films deposited on single crystal substrates
- 2023
-
Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 772
-
Tidskriftsartikel (refereegranskat)abstract
- Thin films of BaZr1-xScxO3-x/2, (0 ≤ x ≤ 0.64), well known as proton conducting solid electrolytes for intermediate temperature solid oxide fuel cell, were deposited by magnetron sputtering. X-ray diffraction analysis of the as deposited films reveals the presence of single-phase perovskite structure. The films were deposited on four different substrates (c-Al2O3, LaAlO3〈100〉, LaAlO3〈110〉, LaAlO3〈111〉) yielding random, (110)- or (100)-oriented films. The stability of the as-deposited films was assessed by annealing in air at 600 °C for 2 h. The annealing treatment revealed instabilities of the perovskite structure for the (110) and randomly oriented films, but not for (100) oriented film. The instability of the coating under heat treatment was attributed to the low oxygen content in the film (understoichiometry) prior annealing combined with the surface energy and atomic layers stacking along the growth direction. An understoichiometric (100) oriented perovskite films showed higher stability of the structure under an annealing in air at 600 °C.
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| 14. |
- Nzulu, Gabriel Kofi, 1974-, et al.
(författare)
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Growth and thermal stability of Sc-doped BaZrO3 thin films deposited on single crystal substrates
- 2023
-
Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 772
-
Tidskriftsartikel (refereegranskat)abstract
- Thin films of BaZr1-xScxO3-x/2, (0 ≤ x ≤ 0.64), well known as proton conducting solid electrolytes for intermediatetemperature solid oxide fuel cell, were deposited by magnetron sputtering. X-ray diffraction analysis of theas deposited films reveals the presence of single-phase perovskite structure. The films were deposited on fourdifferent substrates (c-Al2O3, LaAlO3〈100〉, LaAlO3〈110〉, LaAlO3〈111〉) yielding random, (110)- or (100)-orientedfilms. The stability of the as-deposited films was assessed by annealing in air at 600 ◦C for 2 h. Theannealing treatment revealed instabilities of the perovskite structure for the (110) and randomly oriented films,but not for (100) oriented film. The instability of the coating under heat treatment was attributed to the lowoxygen content in the film (understoichiometry) prior annealing combined with the surface energy and atomiclayers stacking along the growth direction. An understoichiometric (100) oriented perovskite films showedhigher stability of the structure under an annealing in air at 600 ◦C.
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| 15. |
- Pearson, Patrick, et al.
(författare)
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Long term stability and recovery of 3 MeV proton irradiated Cu(In,Ga)Se2 and Cu2 (Zn,Sn)(S,Se)4 thin film solar cells
- 2022
-
Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 741
-
Tidskriftsartikel (refereegranskat)abstract
- In 2017, Cu(In,Ga)Se2 (CIGS), Cu2(Zn,Sn)S4 (CZTS) and Cu2(Zn,Sn)(S,Se)4 (CZTSSe) thin film solar cells were irradiated by our group using 3 MeV protons to investigate the materials’ radiation hardness and subsequent recovery following dark storage. It was observed that the primary losses were in open-circuit voltage (VOC), with the CZTS and CZTSSe being more resistant than the CIGS, also recovering to ∼ 95% of initial performance, compared to ∼ 70% for CIGS after two months dark storage. In 2021 the cells were investigated by external quantum efficiency and current-voltage measurements once again, to investigate further recovery. The CIGS cells had continued to recover, whilst the CZTSSe devices appear to have fully recovered from radiation induced damage, but now suffer from aging-related degradation and exhibit slight bandgap widening over time. The CZTS cells were observed to recover fully from the radiation induced damage, whilst also showing gains in VOC.
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| 16. |
- Petrov, Ivan, et al.
(författare)
-
Obituary: Obituary Professor Joe Greene
- 2022
-
Ingår i: Thin Solid Films. - : ELSEVIER SCIENCE SA. - 0040-6090 .- 1879-2731. ; 763
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 17. |
- Ravensburg, Anna L., et al.
(författare)
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Influence of misfit strain on the physical properties of Fe thin films
- 2022
-
Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 761
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the growth of thin Fe layers on MgAl2O4 (001) and MgO (001) substrates using dc magnetron sputtering. The crystal quality of Fe layers deposited on MgAl2O4 is found to be substantially higher as compared to Fe grown on MgO substrates. The effects of the crystal quality on the magnetic and electric transport properties are discussed.
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| 18. |
- Sawa, Hezekiah B., et al.
(författare)
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Toward improving the performance of Cu2ZnSnS4-based solar cells with Zr, W or sulfurized layers at the SnO2:F/Cu2ZnSnS4 rear interface
- 2024
-
Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 793
-
Tidskriftsartikel (refereegranskat)abstract
- The photovoltaic performance of Cu2ZnSnS4 (CZTS)-based thin film solar cells with transparent back contacts is mainly constrained by the ohmic loss due to degradation of the back contacts at high temperatures required for the growth of the CZTS absorbers. This work has attempted to use ultrathin Zr and W interlayers at the SnO2:F (FTO)/CZTS interface with the purpose of improving the ohmic properties of FTO and hence the performance of solar cells. 20 nm thick Zr and W layers were coated on FTO using direct current magnetron sputtering, followed by heating at 550 °C in a sulfur atmosphere for some of the samples. Inclusion of Zr and W interlayers compromised the transmittance of the FTO back contact, however heating of the samples in a sulfur atmosphere improved the transmittance to values comparable to or better than those of un-heated FTO. Furthermore, heated W/FTO showed a significant improvement in electrical conductivity as observed from Hall effect measurements. To make complete solar cells, CZTS absorber, buffer (CdS) and window (i-ZnO/ZnO:Al) layers were sequentially deposited on the un-heated FTO, Zr/FTO, W/FTO and Mo back contacts. Glow discharge optical emmision spectroscopy confirmed that Zr and W did not diffuse into the absorber and also prevented Na diffusion into the absorber. From the scanning electron microscopy cross sectional analysis, an impovement in the absober grain size and a clear junction between the absorber and FTO with W interlayer were observed. Grazing incident X-ray diffractometry confirmed the polycrystalline nature of the CZTS thin films and indicated the presence of other phases, particularly SnS2. On the resulting solar cell parameters, the inclusion of a W interlayer reduced the series resistance from 4.5 Ωcm to 3.7 Ωcm2. An improvement in short circuit current density (JSC) is also observed, enhancing the efficiency of the solar cells with CZTS/W/FTO to 3.1 % compared to that with CZTS/Mo at 2.7 % and CZTS/FTO at 3.0 %. W was found to improve the external quantum efficiency response and JSC of the solar cells for both backside and frontside light illumination. On the other hand, inclusion of a Zr interlayer (Zr/FTO) only slighlty improved the open circuit voltage, but compromised the JSC compared to FTO and W/FTO back contacts. Thus, the findings of this study demonstrate the prospect for improving the performance of the CZTS-based thin film solar cells through the inclusion of ultrathin Zr and W interlayers between the FTO back contact and CZTS absorber.
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| 19. |
- Smaali, A., et al.
(författare)
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Pulsed laser deposited transparent and conductive V-doped ZnO thin films
- 2020
-
Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 700
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Tidskriftsartikel (refereegranskat)abstract
- ZnO and vanadium-doped ZnO (0.7–4.1 at.%) thin films were deposited onto corning glass substrates by the pulsed laser deposition technique using a KrF excimer laser (λ = 248 nm). The films were deposited at 500 °C under an oxygen pressure of 1 Pa with a laser fluence of 2 J/cm2. The structural, morphological, optical and electrical properties as a function of the dopant atomic concentration were investigated by means of X-ray diffraction, Scanning Electron Microscopy, spectrophotometry, conductivity and Hall measurements. All the doped and undoped films show a preferential orientation along the c-axis with a deterioration at higher doping levels (>4 at. %). Besides, as the doping amount increases the in-plane stress leads to an increase of the c-axis lattice parameter. The films are transparent within the wavelength range 400–1200 nm. The electrical resistivity of the films drops from 8.2 10−3 to 1.3 10−3 Ω cm with an increase in the dopant concentration up to 0.9 at. % and then rises as the dopant level is increased further.
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| 20. |
- Sorar, Idris, et al.
(författare)
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Electrochromism of W-In oxide thin films : Implications for cycling durability
- 2020
-
Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 697
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Tidskriftsartikel (refereegranskat)abstract
- Electrochromic W oxide and W–In oxide thin films were prepared by dual-target reactive DC magnetron sputtering and were cycled voltammetrically in an electrolyte of lithium perchlorate in propylene carbonate. Film degradation was investigated for up to 500 cycles in the voltage ranges 1.5–4.0, 1.7–4.0 and 2.0–4.0 V vs. Li/Li+, and optical transmittance was recorded concurrently. Indium doping was found to be unambiguously detrimental to electrochromic cycling durability, which resolves an outstanding issue related to recently discovered unprecedented durability of potentiostatically pretreated W oxide films backed by In2O3:Sn and gives strong support in favor of beneficial effects of solid-electrolyte interfacial layers.
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| 21. |
- Suntornwipat, Nattakarn, et al.
(författare)
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Rapid direct growth of graphene on single-crystalline diamond using nickel as catalyst
- 2023
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Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 770
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Tidskriftsartikel (refereegranskat)abstract
- Although theoretical investigations indicate that the successful combination of graphene and diamond would give interesting properties, only a limited number of reports dealing with the subject have been published. Here, we present a rapid thermal process (RTP) which involves nickel (Ni) as metal catalyst for a direct growth of graphene on diamond at a temperature of 1073 K for 60 s. This process operates with a combination of a lower temperature and for a shorter duration than what has previously been reported. Thin Ni films of different thicknesses were deposited on top of (100) single-crystalline diamond. After RTP, the coverage of monolayer graphene was found to be around 20% shown by the intensity ratio between the 2D- and G-peak using Raman spectroscopy on 50 nm thick Ni films. In addition, x-ray photoelectron spectroscopy and atomic force microscopy analysis were conducted. For electrical characterization, Hall-effect measurements were performed at temperatures between 80 and 360 K.
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| 22. |
- Tasnadi, Ferenc, et al.
(författare)
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Efficient prediction of elastic properties of Ti0.5Al0.5N at elevated temperature using machine learning interatomic potential
- 2021
-
Ingår i: Thin Solid Films. - : Elsevier Science SA. - 0040-6090 .- 1879-2731. ; 737
-
Tidskriftsartikel (refereegranskat)abstract
- High-temperature thermal stability, elastic moduli and anisotropy are among the key properties, which are used in selecting materials for cutting and machining applications. The high computational demand of ab initio molecular dynamics (AIMD) simulations in calculating elastic constants of alloys promotes the development of alternative approaches. Machine learning concept grasped as hybride classical molecular dynamics and static first principles calculations have several orders less computational costs. Here we prove the applicability of the concept considering the recently developed moment tensor potentials (MTP), where moment tensors are used as materials descriptors which can be trained to predict the elastic constants of the prototypical hard coating alloy, Ti0.5Al0.5N at 900 K. We demonstrate excellent agreement between classical molecular dynamics simulations with MTPs and AIMD simulations. Moreover, we show that using MTPs one overcomes the inaccuracy issues present in approximate AIMD simulations of elastic constants of alloys.
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| 23. |
- Tidholm, Johan, et al.
(författare)
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Accurate prediction of high-temperature elastic constants of Ti0.5Al0.5N random alloy
- 2021
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Ingår i: Thin Solid Films. - : Elsevier Science SA. - 0040-6090 .- 1879-2731. ; 735
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Tidskriftsartikel (refereegranskat)abstract
- Using highly accurate ab initio molecular dynamic simulations we calculate elastic constants of Ti0.5Al0.5N as a function of temperature up to 1500 K and compare the results with those obtained for TiN. We analyze the variation of the materials elastic anisotropy with temperature by calculating directional Youngs moduli and Poisson ratios on the (100), (110) and (111) crystallographic planes. We show that though the elastic moduli of Ti0.5Al0.5N strongly decrease upon heating, the elastic anisotropy increases with temperature unlike in TiN. Since several approximate approaches have recently been utilized to predict elastic constants of Ti0.5Al0.5N at elevated temperature we compare our results with published data and benchmark the different approximate schemes. Giving the fact that Ti(1-x)AlxN is a prototypical system for hard coating applications, we conclude that the recently developed symmetry imposed force constants approach combined with the temperature dependent effective potential method is accurate and computationally cost-effective for this material class.
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| 24. |
- von Fieant, Kristina, et al.
(författare)
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Multi-component (Al,Cr,Nb,Y,Zr)N thin films by reactive magnetron sputter deposition for increased hardness and corrosion resistance
- 2020
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 693
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Tidskriftsartikel (refereegranskat)abstract
- Multi-component nitride thin films in the Al-Cr-Nb-Y-Zr system with non-equimolar composition have been deposited by reactive dc magnetron sputtering. The substrate temperature and substrate bias have been varied, from room temperature to 700 degrees C and from 0 to -200 V respectively. The relationship between these varied growth conditions on the structure, morphology, mechanical and corrosion properties of the films have been probed. All films consisted of a single solid solution with a NaCl-type structure, as shown by X-ray diffraction. However, elemental energy dispersive spectroscopy maps, obtained in the scanning transmission electron microscope, indicated that there could be partial segregation of Al, Cr and Y atoms within the grains. The microstructure of the films became denser, more fine-grained and smoother as the bias and temperature were increased. Nanoindentation showed that the hardness of the films increased with both bias and temperature, reaching a maximum of 27 +/- 2 GPa. The corrosion resistance of the films, studied by performing potentiodynamic polarisation curves in 1 M HCl, was also found to be improved when compared to a commercially available hyper-duplex stainless steel and a ternary reference (Nb,Zr)N thin film as well.
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| 25. |
- Voznyi, Andrii, et al.
(författare)
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Close-spaced sublimation of SnS absorber layers and SnS/CdS heterojunction solar cells with Mo and Ti back metal contacts
- 2020
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 709
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Tidskriftsartikel (refereegranskat)abstract
- Tin sulfide is a promising semiconductor candidate to replace the currently used absorber materials in thin film photovoltaic such as Cu(In,Ga)(S,Se)2 and CdTe devices, which use toxic and scarce elements. However, numerous challenges still remain to approach comparable efficiencies for SnS-based solar cells. In this report, we address the following: (i) impact of growth conditions on phase purity and crystal quality of SnS thin films deposited by close-spaced vacuum sublimation technique; (ii) based on optimized SnS growth conditions, we further fabricate tin sulfide solar cells using traditional CdS buffer and i-ZnO/ZnO:Al bilayers and investigate the impact of molybdenum and titanium back metal contacts on photovoltaic parameters of resulting devices; (iii) finally, using device simulations, we reveal the impact of minority carrier lifetime in the SnS absorber and recombination velocity at the SnS/CdS heterointerface on solar cell parameters, demonstrating that these are the main factors affecting the performance of SnS-based photovoltaic devices.
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