Stable domain propagation in the Gunn effect

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Abstract
The properties of uniformly propagating stable domains are calculated using a constant diffusion coefficient of 178 cm2 sec-1 and an analytic approximation to a recently computed static velocity-field characteristic for gallium arsenide. The static characteristic has a steep slope in the negative resistivity range and then saturates at high fields. Consequently the peak domain field initially increases slowly as the domain velocity is reduced from its maximum value and then increases indefinitely as the domain velocity approaches the saturated drift velocity. Domain shapes are given for a resistivity ρ0 = 1 ω cm. The extreme degrees of depletion and accumulation, the widths of the depletion and accumulation layers and the domain potential are all plotted against the field outside the domain for ρ0 = 1, 5 and 10 ω cm. The domain has a rounded triangular shape which is asymmetric and shows large departures from neutrality at large domain voltages (except when ρ0 << 1 ω cm) but which becomes symmetrical and nearly neutral everywhere at low domain potentials, with a diffusion-limited width of 19 ρ01/2 μm. The domain potential increases slowly at first, with an initial slope of 453 ρ01/2 μm, as the outside field is reduced below threshold and then increases rapidly as the minimum outside field is approached. Consequently the length dependence of the domain potential for a fixed average field is less sensitive to resistivity variations than was found previously (using a schematic three-line static characteristic) and is in better agreement with the experimental data.

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