Estimation of fringing capacitance of electrodes on s.i. GaAs substrate

Capacitances of the electrodes with various patterns on a semi-insulating GaAs substrate were measured and analysed to estimate parasitic capacitances of GaAs devices. The fringing capacitance was a larger fraction of the total capacitance for electrodes with area less than 200 µm square. A simple and practical expression for the capacitance was derived from the experimental results.