Effect of field-dependent diffusion on stable domain propagation in the Gunn effect

Abstract

The properties of uniformly propagating stable domains in gallium arsenide are calculated on the basis of recently computed velocity-field and diffusion-field characteristics. The field dependence of the diffusion coefficient makes the domain velocity larger than the electron drift velocity outside the domain. The velocity difference becomes small when the drift velocity approaches its minimum value because the domain leading edge then approaches total depletion. The velocity difference also becomes small when the drift velocity approaches its peak value. This latter behaviour is qualitatively different from that predicted previously and is due to the close proximity of the peaks of the diffusion-coefficient-field and velocity-field characteristics. The maximum velocity difference increases with decreasing resistivity and is about 25% of the drift velocity in 1 Ω cm material. Plots against outside field of domain velocity, width, peak field, potential, and maximum and minimum electron concentrations are given for sample resistivities of 1, 5 and 10 Ω cm.