Influence of manganese contamination on high-mobility GaAs/AlGaAs heterostructures

Photoluminescence and magnetotransport measurements have been performed to assess the quality of modulation doped GaAs/AlGaAs heterostructures. The temporal evolution of the low-temperature electron mobility of samples prepared in a molecular beam epitaxy chamber containing manganese as a source material was studied. Mn contamination was identified to be responsible for the reduction of the electron mobility to 1 x 10^{6} cm^{2}/Vs and the appearance of a distinct photoluminescence band. In contrast, structures in which this signal is absent reach mobility values of 5.4 x 10^{6} cm^{2}/Vs. This directly proves that the epitaxy of high-mobility electron systems and structures containing GaMnAs layers, in principle, can be combined in one growth chamber.