Dependence of Negative Resistivity on Current Density and Junction Temperature for DDR IMPATT

Negative resistivity of Si and Si_0.9Ge_0.1 DDR IMPATT diode are numerically computed using double iterative method and modified Runge-Kutta method and results are compared for identical input parameters. Simulation is based on simultaneous solution of Poisson´s equation, continuity equation and carrier diffusion equation in addition with the effect of mobile space charge subject to the appropriate boundary conditions at the edges of depletion layer. Effect of junction temperature and current density on resistance is evaluated for optimum performance in CE mode. Peaks of the resistivity profile depend on temperature, bias current and frequency of operation. Results suggest that Si_0.9Ge_0.1 shows more negative resistance than the conventional one, and thus it may be considered as the suitable alternative choice for microwave source.