Nonlinear Electrical Effects and Recombination of the Hot Electrons in Compensated Germanium

Steady state and transient current‐voltage characteristics are studied for Cu‐doped n‐type Ge samples with the upper Cu level (Ec — 0.26) eV partly compensated. The field strength is varied from ∼ 1 V/cm to 104 V/cm. The I‐U curves obtained are sublinear at field strengths above ∼ 100 V/cm. A study is made of the effect of temperature and of the spectrum of the incident light upon both the steady state and the kinetics of the photocurrent. Negative differential conductivity and coherent low frequency oscillations are observed at nitrogen temperatures with high illumination. The nonlinear effects are shown to be due mainly to the reduction of electron concentration in the conduction band. This could be ascribed to the field dependence of α n= the probability of electron capture by the doubly charged Cu ions. In the strong electric fields the crystals are becoming inhomogeneous due to the formation of strong‐ and weak‐field regions. The possible influence of these inhomogenities on the nonlinear effects is discussed and the change of α n= in the strong field is estimated. [Russian Text Ignore].