A simple analysis of stable domain propagation in the Gunn effect

Abstract

An analytical treatment of uniformly propagating stable domains is developed for the case when the electrons have a field-independent diffusion coefficient and follow an arbitrary static velocity-field characteristic exhibiting a negative differential resistivity. For any value of the diffusion coefficient the domain velocity is equal to the electron velocity outside the domain and the peak domain field is determined by a dynamic characteristic which is derived from the static characteristic by a simple geometrical construction. In the limit of zero diffusion the domain consists of a depletion layer triangle to which is added a flat-topped region in long, low-resistivity samples at high bias voltages. Numerical results are given for a schematic three-line static characteristic which is representative of gallium arsenide and the variation of the domain parameters with resistivity, sample length and bias voltage is discussed.