COMPUTER-SIMULATION OF TRANSPORT IN THIN-FILMS

The effect of microstructure on the electrical transport behavior of polycrystalline materials has been investigated by means of both experiment and computer simulation. The experiment was carried out by measuring the resistances of model thin film microstructures. It was found that the topology of the microstructure significantly influences the transport characteristics. The results were compared to the prediction of the current analytical theory (Brick-Layer model), and observed to be in significant disagreement. To overcome the limitation of this analytical theory, a computational methodology was developed to simulate the steady-state electrical transport. Comparison of the simulation results with the experiments shows good agreement. In investigating the transport behavior of polycrystalline films having grain boundary of high resistance, grain size and morphology are found to have two effects on the conduction process. First, they can lead to an increase in the length of the equipotential contours due to the fact that they follow the preexisting grain boundary. Second, the large grains can serve to shunt the flux pass adjacent smaller grains. Both of these effects lead to a decrease in the total resistance as the microstructure departs from a regular Brick-Layer type structure.