Instabilities in n-GaAs Including Chaos and Period 3 Simulated by Numerical Computation

Abstract

In studying current instabilities and chaos in semiconductor n-GaAs under weak photoexcitation, we pay special attention to influences from the carrier diffusion, arising from the space charges trapped near the injecting contacts. We extend the well-accepted two-impurity-level model by including the diffusion current δ J formed by such space charges near the negative contact. Without this δ J , one sees the prototype of period-doubling bifurcation (Feigenbaum scenario) but with unbound and exploding phenomena as the control parameter beyond 10.58 V/cm. Adding δ J in, we remove the unreasonable explosion and have the bifurcation routes to chaos of a current filament interrupted by a stable period 3 near E 0 [3] . Our simulations accurately reproduce the location of E 0 [3] and the Feigenbaum number. From our results, we see that δ J plays the role of providing strong friction and preventing the further increase of the conduction electron concentration from exploding.