Transient behaviour and characteristics of the high-field domain in Gunn-effect diodes

Quasi-linear equations are used to analyse characteristics of a high-field domain in Gunn-effect bulk semiconductors. The analysis shows that the differential mobility appearing in the relaxation time of the large-signal analysis is not the same as that used in the small-signal analysis. It is also shown that an equivalent admittance of domain is represented by a parallel connexion of capacitance and conductance which vary with time in the transient state. The equations for the shape of domain and for the time-constant of the admittance are derived. The width of a high-field domain and the displacement current of diodes are discussed. The maximum value of the domain excess potential in the diode biased at the threshold is given. Numerical examples of characteristics of a high-field domain based on the results of the analysis are presented. It is pointed out that non-linear and parametric operations of Gunn-effect diodes can be interpreted by the use of an expression for admittance of the diode in which the effects of r.f. circuit voltage on the domain are taken into account.