Field Emission Dark Current of Technical Metallic Electrodes

In the framework of the Low Emittance Gun (LEG) project, high gradient acceleration of a low emittance electron beam will be necessary. In order to achieve this acceleration a -500 kV, 250 ns FWHM, pulse will be applied in between two electrodes. Those electrodes should sustain the pulsed field without arcing, must not outgass and must not emit electrons. Ion back bombardment, and dark current will be damageable to the electron source as well as for the low emittance beam. Electrodes of commercially available OFE copper, aluminium, stainless steel, titanium and molybdenum were tested following different procedures including plasma glow discharge cleaning.Comment: 22 pages, 6 tables, 10 figures Vs 2 : graphics more readable, enhanced content Vs 3 : typo correcte

Optimization of gas injection conditions during deposition of AlN layers by novel reactive GIMS method

In 2011, we proposed a novel magnetron sputtering method. It involved the use of pulsed injection of working gas for the initiation and control of gas discharge during reactive sputtering of an AlN layer (Gas Injection Magnetron Sputtering – GIMS). Unfortunately, the presence of Al–Al bonds was found in XPS spectra of the AlN layers deposited by GIMS onto Si substrate. Our studies reported in this paper proved that the synchronization of time duration of the pulses of both gas injection and applied voltage, resulted in the elimination of Al–Al bonds in the AlN layer material, which was confirmed by the XPS studies. In our opinion the most probable reason of Al–Al bonds in the AlN layers deposited by the GIMS was the self-sputtering of the Al target in the final stage of the pulsed discharge

Effect of pulsed magnetron sputtering process for the deposition of thin layers of nickel and nickel oxide

Magnetron sputtered nickel and nickel oxide films have been studied for various applications. We may find, among others, these films in electrochromic display devices, in resistive type gas sensors, as metal electrodes in electronic devices, in solar thermal absorbers. Pure nickel films deposited using PVD technique possess good corrosion and wear resistant properties. Magnetron sputtering has several advantages in film deposition (in comparison to other methods) such as relatively low heating temperature of the deposited substrate during sputtering process, high energy of sputtered atoms (about 10 eV) at the substrate, which influences positively the films adhesion. From application point of view, the most valuable feature of these films is the possibility of scaling target dimensions, which makes feasible the deposition on a several square meter surfaces. The improvement of magnetron sputtering devices design may influence positively the optimization of the deposition technology and its efficiency. The thin nickel and nickel oxide films were prepared by pulsed magnetron sputtering using original type WMK magnetron device. Ni (99.9 %) has been used as a sputtering target of 100 mm in diameter and different thicknesses (3 mm, 5 mm, and 6 mm). The distance between the substrate and target was the same in all experiments and equal to 120 mm. Argon and oxygen gases were introduced during the reactive process through needle gas valves at a total pressure of 0.4 Pa. The sputtering power, sputtering pressure and oxygen partial pressure have been used as technological knobs for deposition processes. The helpful tool for controlling the pulsed magnetron sputtering process was the original parameter of supply (so called circulating power). Results from our experiments showed that the deposition of Ni films is possible even from targets of 6 mm thickness. Deposition rate increased proportionally with the sputtering power. The aim of this work is to use the acquired expertise to develop an efficient technology of thin nickel oxide layers for electrochromic systems

Analysis of properties of thin TiO2 layers for application in photovoltaic and optoelectronic devices

Artykuł jest opisem analizy nowej metody nakładania cienkich warstw dwutlenku tytanu pod kątem jej aplikacji w ogniwach słonecznych z uwzględnieniem elastycznych struktur fotowoltaicznych. Uzyskane warstwy zostały poddane zarówno charakteryzacji optycznej i elektrycznej, jak również badaniom strukturalnym w celu weryfikacji możliwości ich zastosowań w charakterze emiterowych pokryć przewodzących w strukturach fotowoltaicznych. Dodatkowo, w ramach oceny potencjału zastosowania TiO2 w elastycznych ogniwach słonecznych, badane warstwy otrzymane na elastycznych podłożach PET zostały przetestowane pod kątem wpływu dynamicznych cykli zginania na zmianę ich rezystancji na kwadrat. Jako ostateczna weryfikacja potencjału uzyskanych warstw do produkcji przyrządów fotowoltaicznych wykonano prototypowe ogniwo słoneczne, pokryte TiO2, oraz sprawdzono jego podstawowe parametry elektryczne.This paper presents properties of titanium dioxide thin films prepared in reactive pulse magnetron deposition method using differential variants of process parameters. Layers of TiO2 were deposited on both glass and polymer foil substrates. They were characterized in terms of optical and electrical parameters in order to verify their possible application as emitter conductive coatings in photovoltaic structures. Additionally, within the evaluation process of potential TiO2 application in flexible solar cells, layers deposited on PET foils, were investigated for mechanical durability. They were tested in terms of the influence of dynamic bending cycles on surface resistance per square changes