Measurements on the electrical resistivity of thin metallic films

Abstract

Going on with our experiments on the electrical resistivity of thin nickel films, we are at present interested about the influence of the formation conditions on the electrical resistivity. It has been established by.different investigators 1) and also by us ~), that the metal for a small thickness passes from the conducting state to that of a semi-conductor. The temperature coefficient as a function of thickness e.g. at room temperature, passes through zero at a certain thickness, corresponding to a critical resistance R c, and becomes negative for thinner films. This phenomenon is very pronounced for nickel films. To realise those films two differents methods are used in our laboratory: cathodic sputtering and condensation in vacuum. The two apparatus used are represented in fig. 1 and 2. For the experimental technique we refer to our previous papers. At present we studied first the dependence of the critical resistance on the kind of gas used in the cathodic discharge. Also we examined the influence on Rc of the vacuum degree when using the condensation method. Our films are deposited on rectangular supports in pyrex glass: length of the film 15 mm, Width 3,5 mm. For the sputtering of our films we used the following gases: He, H2, Ar, Ne and N 2, under the same gas pressure (10 t mm Hg, except for He; 5.10 l mm) and the same voltage (3.000-4.000 V).