Two-dimensional Gunn-domain dynamics

In two-dimensional bulk GaAs devices, each small segment of a high-field domain can be considered to move normal to its front, with a velocity equal to that of a one-dimensional domain having the same domain potential. Using this simple model, an equation describing the domain shape in two-dimensional samples was obtained. When edge nucleation effects are taken into account, the solution of the equation provides a good explanation for most of the domain motions observed experimentally in various samples of non-uniform shape. The experimental observations were made using a resistive probe. The probe experiments enable one to visualize how domains behave in devices with sudden or gradual changes in width, with sharp or gradual bends, and with multiple terminals. In an Appendix, the simple model of two-dimensional domains is justified using a perturbation theory.