Current oscillations induced by recombination instability in semiconductors

We present a one-dimensional system of gold-doped n-Ge in which the recombination instability leads the system to instability and current oscillations. Using the finite difference method, spatio-temporal evolution of the high-field domain is computed with the bias voltage, the recombination coefficient, and the emission coefficient being taken as the control parameters. Three types of modes of operation: the Ohmic, the quenched and the transit-time modes are found. Non-periodic oscillations are also found in the transition region between the quenched and the transit-time modes. Their origins are clarified on the basis of spatio-temporal evolution of the high-field domain.