Non-Activated Conductivity of Hot Electrons in Localization Regime |
| J. Łuskowski and M. Grynberg Institute of Experimental Physics, University of Warsaw, Hoża 69, 00-681 Warszawa, Poland |
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| Temperature (T) dependence of conductivity (σ) was studied in semi-insulating GaAs as a function of the magnetic field (B) for 1.8 K < T < 40 K for high electric fields. An infrared illumination of a sample and application of an electric field caused a non-equilibrium distribution of electrons in the conduction band. An increase in B caused a localization transition which manifested itself by a gradual disappearance of the impact ionization of shallow bound states. The transition was connected with a change from a non-activated to an activated conductivity only if T > 4 K, otherwise σ showed only a non-activated character. It is proposed that for T < 4 K the electron distribution function is mostly determined by optical and electric field excitations, which results in a non-activated conductivity. For T > 4 K thermal excitations become dominant which leads to an activated character of σ. |
| DOI: 10.12693/APhysPolA.87.253 PACS numbers: 72.20.My, 72.20.Ht |