An equivalent network for resistance and temperature coefficient of resistance versus temperature and composition of thick resistive films

Two types of elementary resistances in thick resistive films have been considered: (i) constriction resistance RC determined by the bulk properties of conducting material and by the geometry of constriction, and (ii) barrier resistance RB determined by the parameters of a thermally activated type of tunneling process and by the geometry of the metal-insulator-metal unit. On this basis a resistance network composed of a large number of the two types of resistances has been defined. The network has been considered as being equivalent to thick resistive film (TRF) from the point of view of the resistance and temperature coefficient of resistance (TCR). The parameters of this network have been evaluated by the computer-aided approximation of the experimental data found for RuO2-based TRFs. On the basis of the equations derived for the network as well as the results of the approximation process, it can be concluded that the small values of the network TCR result from the superposition of the TCR of the conducting component βC and of the temperature coefficient of barrier resistance αB. In this superposition βC is attenuated (by 1–2 orders of magnitude), while αB is attenuated by only few percentages. The network has been found to be strongly barrier dominated.