Si3N4 thin films were prepared by RF magnetron sputtering using N2 or Ar as the sputtering gas. The films were amorphous, with the deposition rate for Ar-sputtered films increasing with RF power and Ar pressure. Sandwich samples having both Al and Au electrodes were prepared. Capacitancevoltage measurements indicated that the contacts for Nj-sputtcred samples were ohmic, while Ar-sputtered samples with Al electrodes exhibited depletion regions. Values of the relative permittivity of 6.3 (AI electrodes) and 6.8 (Au electrodes) were determined from geometric capacitance variations in Ny-sputrered films. Current density-voltage characteristics normally showed ohmic and space charge limited conductivity with trap levels distributed exponentially within the insulator band gap, but exceptionally in N2-sputtered films with Au electrodes electroforming behaviour was observed, with Poole-Frenkel conductivity in the preformed region. Hopping was dominant at low temperatures. AC conductivity was higher for Ar-sputtering, and with Au electrodes. These effects were related to the possible structure of the films, and the diffusion of Au. AC conductivity increased with increasing frequency and temperature, appearing to be via a free band process at high temperatures and hopping at low temperatures. Plausible values of the density of localised states were deri ved using Elliott's model, but this could not be considered uni versally applicable. Loss tangent was also frequency and temperature dependent in Ny-sputtered films, showing a minimum value which shifted towards higher frequencies with increasing temperature. In Ar-sputtered samples minima were not observed in the frequency range covered. The model of Goswami and Goswami appears consistent with these results, particularly in the former case. Variations in the loss tangent values with the sputtering gas and electrode species were consistent with the observed conducti vity variations. Optical properties were also investigated. In Ar-sputtered films, the optical band-gap appeared narrower and the optical absorption higher than for Ny-sputtered films, and a direct transition was also identified. Values of the electrical properties determined for such sputtered films are comparable to those prepared using more sophisticated methods, particularly in the case of Nj-sputtered films. Sputtering may therefore prove useful in semiconductor processing, where a relatively inexpensive method of deposition is required.

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We investigated thin film samples of Mg2NiH4 with two intentions. First of all, we wanted to ascertain if the same nanomaterial (Mg2NiH4) prepared by magnetron sputtering and ball milling can exhibit different hydrogen storage properties and to see possible advantages/disadvantages of employing of magnetron sputtering for synthesis of nanometerials for hydrogenstorage. Furthermore, we wanted to see if thin film samples of Mg2NiH4 could be used in a switchable mirror or window device by utilizing the high to low temperature transition at about 510 K. In powder samples, this transition, between a monoclinic conducting low temperature phase to an FCC non-conducting high temperature phase, have been demonstrated in a mechanical reversible conductor–insulator transition [Blomqvist and Nor��us, J. Appl. Phys 91(2002)5141]. The new thin film Mg2NiH4 samples were produced by reacting hydrogen with magnetron sputtered Mg2Ni films on quartz glass or CaF2 substrates. But we could not obtain the monoclinic low temperature phase upon cooling the samples. Instead a cubic phase, related but not identical to the cubic high temperature phase, was formed at temperatures both below and above 510 K. TEM pictures revealed the new cubic phase in the films to have the same cell parameter as the FCC high temperature phase. But the symmetry was lower with similar streaking patterns as observed for the monoclinic low temperature phase. IR-spectroscopy indicated an identical vibrational frequency for... [to full text] / Tiriamojo darbo metu magnetroniniu garinimu suformuotos Mg-Ni dangos, kurios hidrintos esant aukštai temperatūrai ir vandenilio slėgiui. Hidrintos dangos ištirtos įvairiais analizės metodais, siekiant nustatyti magnetronio garinimo būdu suformuotos medžiagos (magnio nikelio hidrido) skirtumus nuo rutulinio trynimo metodu gautos analogiškos medžiagos. Darbe išanalizuoti duomenys ir pateiktas aiškinamasis modelis, kuris atskleidžia plonų dangų ypatybes, dėl kurių dangose pilnai neįvyksta dangos relaksacijos procesai. Nustatyta, kad dėl tų pačių priežasčių, dangų panaudojimo „įjungiamiesiems veidrodžiams“ galimybės yra ribotos.

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