Discussion Forum

My name is John and I have created a 2D model in COMSOL consisting of two rectangular Copper electrodes seperated by a Silicon Dioxide thin film 0.5 um to 2 um thick. Using the Electric Currents (ec) physics in the AC/DC module, I made the top Copper electrode a domain terminal (voltage type) with a 1 V potential applied. I then made the bottom electrode a domain probe to measure voltage. Using the Frequency Domain Study, I wanted to apply the voltage to the top electrode at different frequencies ranging from 1 Hz to 1 MHz and observe the subsequent potential difference on the bottom electrode as a function of both frequency and Silicon Dioxide film thickness. The results showed that the potential on the bottom electrode increases with increasing signal frequency which seems logical. However, the results also show that the potential on the bottom electrode increases with increasing film thickness which does not seem logical if you consider the film as a resistive element. The result of increasing potential on the bottom electrode with increasing film thickness could be explained if the model is thought of as a parallel plate capacitor where increasing the distance between the plates corrosponds to a decreace in capacitance which corrosponds to an increase in the potential difference across the plates. I was hoping that someone could offer suggestions on how to better model the resistive current flow through a Silicon Dioxide thin film as opposed to the capacitive current flow, or a way to simulate/analyze both resistve and capacitive current flow through the thin-film simultaneously. Any help is greatly appreciated.