The chaos under dc voltage bias linked with multiple shedding of wave fronts were numerically simulated. Space charge wave dynamics was analyzed with a finite-dimensional model. Drift diffusion model of space charge wave propagation in semiconductors was studied. The dynamics of space charge waves and current vs time were explained by asymptotic analysis of a partial differential equation model. It was found that single or multiple wave shedding during each oscillation depend on resistivity of the injecting contacts.