NONLINEAR ELECTRON-TRANSPORT IN SI DELTA-DOPED GAAS

In this paper we report abnormal non-ohmic behaviour observed in Si de lta-doped GaAs. We have performed measurements in Hall bar and Van der Pauw geometries in which electron transport phenomena can be studied by looking into the dependence of the device resistance R(xx) on the a pplied current I or input power per electron, P. Transport of electron s in single Si delta-doped layers in GaAs, grown by MOCVD, in the line ar and non-linear response regimes was studied. Our experimental resul ts show that: i) R(xx) dramatically decreases with increasing I (P) wh en sample current (input power) is larger than a critical value I-c (P -c); ii) I-c increases with electron density (Si delta-doping concentr ation); and iii) the decrease in R(xx) with increasing I in the non-li near response regime can be observed both at zero and high magnetic fi elds over a wide temperature range. When R(xx) is plotted as a functio n of the power loss rate per electron (P) the values of the critical p ower (P-c) for different samples are roughly the same; We suggest that redistribution of the ionised donors in the sample occurring when I > I-c takes the major responsibility for the observed abnormal phenomen a.