SUPPRESSION OF THE LOCALIZATION IN THE 2-DIMENSIONAL CONDUCTIVITY OF SI-DELTA-DOPED GAAS BY MN CO-DOPING

We present low-temperature magnetotransport investigations of the 2D-c onductivity in Si-delta-doped GaAs samples where the donors are strong ly compensated by Mn accepters. It is shown that the compensation by M n accepters effects ii) a suppression of the decrease of conductivity caused by the effect of weak localization, (ii) the saturation of the phase relaxation time tau(phi) at low temperature and (iii) a non-occu rrence of the metal-insulator transition under the application of a hi gh magnetic held and on lowering the electron density. The effects (i) and (ii) are explained taking into account that doping with Mn leads to the appearance of localized magnetic moments. To explain (iii) we s peculate that the spatial distribution of Mn accepters and Si-donors i s correlated resulting in a smoothing of the fluctuation of the scatte ring potential. (C) 1998 Elsevier Science B.V. All rights reserved.