Small-carrier perturbations close to the unperturbed bulk are analyzed which represent boundary conditions for the perturbations produced by injection and extraction in thick enough semiconductor samples. On this basis concentration contours for the strong-perturbation range can be qualitatively drawn and even numerically evaluated. The results allow for a clear distinction to be made between lifetime and relaxation behavior. There is also an intermediary regime between these, and within it a new kind of steady state with oscillations in space is proved to be possible for appropriately chosen currents. Two new conditions have also been evidenced for the high current conduction in the asymptotic range: "equality recombination" in the deep-lifetime case, and "unperturbed conductivity" in the deep-relaxation case. Necessary conditions for obtaining an increase in resistance through injection have also been outlined.

• Received 25 May 1977

DOI:https://doi.org/10.1103/PhysRevB.17.3972