Nonlinear electron transport in Si δ-doped GaAs

Abstract

In this paper we report abnormal non-ohmic behaviour observed in Si δ-doped GaAs. We have performed measurements in Hall bar and Van der Pauw geometries in which electron transport phenomena can be studiekd by looking into the dependence of the device resistance Rxx on the applied current I or input power per electron, P. Transport of electrons in single Si δ-doped layers in GaAs, grown by MOCVD, in the linear and non-linear response regimes was studied. Our experimental results show that: i) Rxx dramatically decreases with increasingI (P) when sample current (input power) is larger than a critical value Ic (Pc); ii) Ic increases with electron density (Si δ-doping concentration); and iii) the decrease in Rxx with increasing I in the non-linear response regime can be observed both at zero and high magnetic fields over a wide temperature range. When Rxx is plotted as a function of the power loss rate per electron (P) the values of the critical power (Pc) for different samples are roughly the same. We suggest that redistribution of the ionised donors in the sample occurring when I >Ic takes the major responsibility for the observed abnormal phenomena.