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In this work, several applications of time resolved absorption spectroscopy, with different time scales and spectral resolutions, are described for the diagnostic and modeling of cold plasmas produced in square wave modulated hollow cathode discharges. These methods have revealed a very sensitive and efficient way to test the relevance of the different individual mechanisms, in comparison with the...
This paper describes part of a work carried out to develop new ternary M-M1-C systems (M=metal of the Groups IV-VI and M1=Group VIII element) by sputtering. The results obtained in this study on Ti-Fe-(C) and Mo-Fe-(C) systems showed that, depending on the type and content of iron, the obtained materials are structurally metastable, formed either by structures with enlarged solubility domains or amorphous...
The study of thermal behaviour of Ti(dpm) 2 (OPr i ) 2 used as a source compound to obtain TiO 2 films was carried out. Data on vapour composition, thermal stability and decomposition products of the compound in vacuo were obtained. The scheme of thermal decomposition of vapour on hot surface is suggested. Photocatalytic TiO 2 films on glass and quartz substrates...
Hydrogenated amorphous silicon (a-Si:H) thin films have been deposited on glass and crystalline silicon substrates by magnetically confined RF-PECVD (MC-RF-PECVD) at different RF power densities in order to verify the influence of this deposition parameter on the density of states (DOS) and growth rate (R G ). It was found that the highest growth rate, 7.8Å/s, is obtained for a-Si:H films...
We have modelled a p-i-n image sensor under local illumination through a two-dimensional non-linear circuit. The sensor is described as an array of photodiodes interconnected through lateral resistors, which model the sheet resistance of the doped layers. Under small-signal analysis, each photodiode is modelled by a current-controlled resistor proportional to the inverse of the photocurrent. A SPICE...
We report, for the first time, results on transparent ZnO:Al thin films deposited on polyester (Mylar type D, 100μm thickness) substrates at room temperature by magnetron sputtering. The structural, optical and electrical properties of the deposited films have been studied. The samples are polycrystalline with a hexagonal wurtzite structure and a strong crystallographic c-axis orientation (002) perpendicular...
The interaction of the azidoacetic acid, N 3 CH 2 COOH, with an Ag (111) crystal modified by surface carbon has been observed. XPS measurements of C (1s), O (1s), N (1s) and Ag 3d 3/2,5/2 as a function of the exposure have been used to follow the predominant species rising with the azide adsorption. Dissociative chemisorption occurs at room temperature...
Plasma technologies offer a wide spectrum of possible treatments of materials. In particular, in function of the peculiar physical characteristics of the plasma, produced by different ionisation systems, three types of processes on the materials can be activated: (1) Destruction of toxic/harmful materials; (2) Superficial modification of existing materials; (3) Creation of new materials.Thermal plasma...
Hollow magnetron cathodes are particularly useful in coating parts with cylindrical symmetry and when deposition must be centripetal; this is the case when coating the outside of tubular and long substrates. A hollow magnetron cathode and its vacuum system has been designed and constructed to coat 2m long heat pipe absorbers and fluid pipe absorber tubes with a selective film of aluminum nitride....
Experimental and theoretical studies of sputtered atoms transport, between target and substrate, give some understanding about the behaviour of the deposition rate in magnetron cathode glow discharges. The present work refers to an experimental study about the dependence of deposition rate, R, on pressure, in an Ar magnetron discharge on a Cu target, at a pressure range extending from 10 to 67Pa....
The surface of a solid barium sample has been studied by surface analysis techniques. The procedure to obtain a clean surface is discussed. In depth distribution of the sputtered ions during cleaning provides a good way to understand the evolution in the surface composition. Ion images show clear differences in the composition of the sputtered spot relatively to the adjacent area. The acquisition...
Amorphous glass/ZnO:Al/p(a-Si:H)/i(a-Si:H)/n(a-Si 1-x C x :H)/Al imagers with different n-layer resistivities were produced by plasma enhanced chemical vapour deposition technique (PE-CVD). The image is projected onto the active surface of the sensor and defines itself spatially confined depletion regions that can be readout by scanning the photodiode with a low power modulated...
A versatile data acquisition and control system (DACS) of general application in physical vapor deposition equipment for thin films growth has been designed and developed. Based on a common and inexpensive hardware, a modular conception of the software allows the system to be easily adapted to control a variety of devices and therefore to be used for a number of applications with very light adjustments...
In this paper we report results of nanocrystalline p-doped silicon films produced by hot wire chemical vapour deposition technique with Ta filaments, using a pre-mixed gas containing silane, diborane, methane, helium and hydrogen. The data obtained show that the films produced exhibit good optoelectronic properties and show a surface morphology dependent on the filament temperature and hydrogen dilution...
High temperature processing is currently present in the industrial production of advanced functional coatings. This paper discusses the role of residual stress on the mechanical integrity of PVD protective coatings. A numerical model of the residual stress distribution within a layered metal-ceramic composite coating is presented. The stress-induced failure modes are analysed. Residual stress distribution...
Ion beam assisted deposition (IBAD) techniques have been employed to produce thin films composed of boron, carbon, and nitrogen atoms, including amorphous carbon (a-C), carbon nitride (CN x ) and ternary compounds (BC x N y ). The films were deposited by evaporating either graphite or boron carbide (B 4 C) targets, with simultaneous ion bombardment from a precursor...
In the present work we present a study of ZrO 2 /Al 2 O 3 multilayers prepared by DC reactive sputtering with different ZrO 2 layer thicknesses. To test their thermal stability, the multilayers were annealed at high temperature. A possible reason for the tetragonal phase to be stabilised in the multilayers is discussed. X-ray diffraction and Raman spectroscopy have...
Nanocrystalline thin films of MnFe 2 O 4 (MFO) and La 0.67 Sr 0.33 MnO 3 (LSMO) were deposited by r.f. reactive sputtering and subsequent annealing forming a heterostructure composed of MFO/LSMO/MFO. Quick MFO thin films saturation and saturation magnetization value are decisive factors that make this technique efficient and useful...
The aim of the present work is to elucidate the role played by lithium impurities in the D 2 O adsorption on MgO(100) surfaces at room temperature and on H and D diffusion processes by using electron stimulated desorption (ESD). The growth of the D 2 O layer has been studied by recording the intensity of O + , OD + and D + desorbed ions. Whereas for undoped...
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