Some measurements of the steady-state and transient characteristics of high-field dipole domains in GaAs

The current response of a long GaAs Gunn diode is observed following a step function of voltage applied while a domain is in transit. The excess domain voltage, the apparent charge of one sign stored on the domain, and the peak field in the domain are measured using this technique. These measurements are compared with other results obtained from more direct, high resolution capacitive probe measurements made on oscillating GaAs specimens. Both sets of measurements are compared with the predictions of "invariant domain" calculations. The measured domain voltages are found to be higher than predicted by theory. The differential capacity associated with a domain is about half that predicted by the simple zero diffusion model. Reasons for these results are advanced.