Konstanty Marszałek

Optical properties of the Al2O3/SiO2 and Al2O3/HfO2/SiO2 antireflective coatings

Investigations of bilayer and trilayer Al2O3/SiO2 and Al2O3/HfO2/SiO2 antireflective coatings are presented in this paper. The oxide films were deposited on a heated quartz glass by e-gun evaporation in a vacuum of 5 × 10−3 [Pa] in the presence of oxygen. Depositions were performed at three different temperatures of the substrates: 100 °C, 200 °C and 300 °C. The coatings were deposited onto optical quartz glass (Corning HPFS). The thickness and deposition rate were controlled with Inficon XTC/2 thickness measuring system. Deposition rate was equal to 0.6 nm/s for Al2O3, 0.6 nm − 0.8 nm/s for HfO2 and 0.6 nm/s for SiO2. Simulations leading to optimization of the thin film thickness and the experimental results of optical measurements, which were carried out during and after the deposition process, have been presented. The optical thickness values, obtained from the measurements performed during the deposition process were as follows: 78 nm/78 nm for Al2O3/SiO2 and 78 nm/156 nm/78 nm for Al2O3/HfO2/SiO2. The results were then checked by ellipsometric technique. Reflectance of the films depended on the substrate temperature during the deposition process. Starting from 240 nm to the beginning of visible region, the average reflectance of the trilayer system was below 1 % and for the bilayer, minima of the reflectance were equal to 1.6 %, 1.15 % and 0.8 % for deposition temperatures of 100 °C, 200 °C and 300 °C, respectively.

In-situ TEM heating of Ni/Al multilayers

Abstract Ni/Al multilayer coatings of period Λ = 110 nm and Λ = 16 nm were deposited using a double target magnetron system. Their microstructure was characterized by means of transmission electron microscopy using thin foils cut out with a focused ion beam. Next, thin foils were subjected to in-situ heating up to 550 °C or 600 °C at a rate of 100 K min–1. Phase changes were followed with the help of the electron diffraction method. The experiments helped to establish that for the large period (Λ∼110 nm) multilayer the reaction starts at 350 °C at Ni/Al internal interfaces through precipitation of the Al9Ni2 phase, which at 500 °C is substituted with NiAl phase. The small period multilayers (Λ∼16 nm) subject to heating react at an even lower temperature of 300 °C by direct precipitation of the NiAl phase. The latter reaction seems to start within the whole nickel layer simultaneously.

Wide band antireflective coatings Al2O3 / HfO2 / MgF2 for UV region

Deposition technology of the three layers antireflective coatings consists of hafnium compound are presented in this paper. Oxide films were deposited by means of e-gun evaporation in vacuum of 5x10-5 mbar in presence of oxygen and fluoride films by thermal evaporation. Substrate temperature was 250°C. Coatings were deposited onto optical lenses made from quartz glass (Corning HPFS). Thickness and deposition rate were controlled by thickness measuring system Inficon XTC/2. Simulations leading to optimization of thickness and experimental results of optical measurements carried during and after deposition process were presented. Physical thickness measurements were made during deposition process and were equal to 43 nm/74 nm/51 nm for Al2O3 / HfO2 / MgF2 respectively. Optimization was carried out for ultraviolet region from 230nm to the beginning of visible region 400 nm. In this region the average reflectance of the antireflective coating was less than 0.5% in the whole range of application.

Graphene platelets as morphology tailoring additive in carbon nanotube transparent and flexible electrodes for heating applications

Flexible and transparent electrodes were fabricated with spray coating technique from paints based on multiwalled carbon nanotubes with the addition of graphene platelets. The work presents the influence of graphene platelets on the paints rheology and layers morphology, which has a strong connection to the electrooptical parameters of the electrodes. The paints rheology affects the atomization during spray coating and later the leveling of the coating on the substrate. Both technological aspects shape the morphology of the electrode and the distribution of nanoparticles in the coating. All these factors influence the sheet resistance and roughness, which is linked to the optical transmission and absorbance. In our research the electrode was applied as a transparent and elastic heating element with 68% optical transmission at 550 nm wavelength and 8.4 kΩ/• sheet resistance. The elastic heating element was tested with a thermal camera at the 3 diverse supply voltages -20, 30, and 60 VDC. The test successfully confirmed and supported our proposed uses of elaborated electrodes.

Carbon nanomaterials dedicated to heating systems

Purpose – The paper aims to present the research results related to transparent heating elements made from carbon nanomaterials. Heating elements were fabricated only with cost-effective techniques with the aim to be easily implemented in large area applications. Presented materials and methods are an interesting alternative to vacuum deposition of transparent resistive layers and etching of low-resistive patterns. Fabricated heating elements were designed to be used as de-icing structures in roof-top windows. Design/methodology/approach – The paper presents the research results related to transparent heating elements made from carbon nanomaterials. Heating elements were fabricated only with cost-effective techniques with the aim to be easily implemented in large area applications. Presented materials and methods are an interesting alternative to vacuum deposition of transparent resistive layers and etching of low-resistive patterns. Fabricated heating elements were designed to be used as de-icing structu...

Performance Analysis of Crystalline Silicon and CIGS Photovoltaic Modules in Outdoor Measurement

Abstract The outdoor measurements (during two months experiment) of photovoltaic silicon and CIGS modules as well as simulation of energy production during the period experiment are presented in this paper. This paper offer comparison of construction and electrical characteristics of multicrystalline silicon based modules and CIGS based modules. The measuring system for PV modules efficiency research is shown. The nominal power of installed modules is 250 W for m-Si and 280 W for CIGS modules. The energy production in outdoor conditions at direct current side and alternating current side of each photovoltaic panel was measured. Each PV panel was also equipped with temperature sensor for screening panel temperature. The photovoltaic panels were connected to the electrical network with micro inverters. To determine the influence of irradiance at sunshine on power conversion efficiency of PV panels, the pyranometer was installed in the plane of the modules. Measurement of the instantaneous power and irradiance gave the information about the efficiency of a particular photovoltaic panels. In the paper all data from research installation were analysed to present the influence of solar cell technology on the power conversion efficiency. The results of energy production show that m-Si module produced more energy from square meter (30.9 kWh/m2) than CIGS module (28.0 kWh/m2). Thin film module shows the higher production per kWp than multicrystalline module: 217.3 kWh/kWp for CIGS and 201.9 kWh/kWp for m-Si. The energy production simulation (made by PV SOL software and outdoor measurements test are in the good agreement. Temperature power coefficient for the CIGS module is twice lower than for the multicrystalline silicon module: 0.56%/°C and 0.35%/°C for m-Si and CIGS modules, respectively. The obtained results revealed strong influence of irradiance and temperature on energy production by PV panels. Performed studies have a large field of potential application and could improve designing process of PV installation.

Structural investigation of MF, RF and DC sputtered Mo thin films for backside photovoltaic electrode

Recently photovoltaics attracts much attention of research and industry. The multidirectional studies are carried out in order to improve solar cells performance, the innovative materials are still searched and existing materials and technology are optimized. In the multilayer structure of CIGS solar cells molybdenum (Mo) layer is used as a back contact. Mo layers meet all requirements for back side electrode: low resistivity, good adhesion to the substrate, high optical reflection in the visible range, columnar structure for Na ions diffusion, formation of an ohmic contact with the ptype CIGS absorber layer, and high stability during the corrosive selenization process. The high adhesion to the substrate and low resistivity in single Mo layer is difficult to be achieved because both properties depend on the deposition parameters, particularly on working gas pressure. Therefore Mo bilayers are applied as a back contact for CIGS solar cells. In this work the Mo layers were deposited by medium frequency sputtering at different process parameters. The effect of substrate temperature within the range of 50°C-200°C and working gas pressure from 0.7 mTorr to 7 mTorr on crystalline structure of Mo layers was studied.

Antireflective bilayer coatings based on Al2O3 film for UV region

Abstract Bilayer antireflective coatings consisting of aluminium oxide Al2O3/MgF2 and Al2O3/SiO2 are presented in this paper. Oxide films were deposited by means of e-gun evaporation in vacuum of 5 × 10-3 Pa in the presence of oxygen, and magnesium fluoride was prepared by thermal evaporation on heated optical lenses made from quartz glass (Corning HPFS). Substrate temperature was maintained at 250 _C during the deposition. Thickness and deposition rate were controlled with a thickness measuring system Inficon XTC/2. The experimental results of the optical measurements carried out during and after the deposition process have been presented. Physical thickness measurements were made during the deposition process and resulted in 44 nm/52 nm for Al2O3/MgF2 and 44 nm/50 nm for Al2O3/SiO2 system. Optimization was carried out for ultraviolet region with minimum of reflectance at 300 nm. The influence of post deposition annealing on the crystal structure was determined by X-ray measurements. In the range from ultraviolet to the beginning of visible region, the reflectance of both systems decreased and reached minimum at 290 nm. The value of reflectance at this point, for the coating Al2O3/MgF2 was equal to R290nm = 0.6 % and for Al2O3/SiO2R290nm = 1.1 %. Despite the difference between these values both are sufficient for applications in the UV optical systems for medicine and UV laser technology.

Characterisation and application of WO3 films for electrochromic devices

Electrochromic system is the one of the most popular devices using color memory effect under the influence of an applied voltage. The electrochromic system was produced based on the thin WO3 electrochromic films. Films were prepared by RF magnetron sputtering from tungsten targets in a reactive Ar+O2 gas atmosphere of various Ar/O2 ratios. The technological gas mixture pressure was 3 Pa and process temperature 30°C. Structural and optical properties of WO3 films were investigated for as-deposited and heat treated samples at temperature range from 350°C to 450°C in air. The material revealed the dependence of properties on preparation conditions and on post-deposition heat treatment. Main parameters of thin WO3 films: thickness d, refractive index n, extinction coefficient k and energy gap Eg were determined and optimized for application in electrochromic system. The main components of the system were glass plate with transparent conducting oxides, electrolyte, and glass plate with transparent conducting oxides and WO3 layer. The optical properties of the system were investigated when a voltage was applied across it. The electrochromic cell revealed the controllable transmittance depended on the operation voltage.

The structure and phase composition of Co/Cu bilayers - sensing elements for magnetoresistive application

Experiments were carried out on single films of Co and Cu, and on Co-Cu bilayers evaporated on the NaCl(001) substrates at room temperature. A thickness of single films, measured by interferometry method, has been changed from 3 to 40 nm for Cu and from 5 to 40 nm for Co. The Transmission Electron Microscope studies showed that at annealing temperatures below 600 K the films consist of fcc Cu and hcp Co. After annealing at higher temperatures, besides the presence of phases already observed at lower temperatures, also Co-Cu solid solution together with single phase of hcp Co was observed.