The effect of HF and H2SO4 + H2O2 treatments on the electrical behaviour on Al/n-SiGe junctions prepared by MBE on n-Si substrates were studied. Barrier heights of 0.73 +/- 0.03 eV and 0.46 +/- 0.04 eV, respectively, were obtained. Misfit dislocations located at the SiGe/Si interface yielded different anomalies of the electrical behaviour, as excess currents, instabilities, and anomalous temperature dependence of electrical characteristics and evaluated parameters. It is shown that in spite of anomalies, the electrical measurements can provide useful and reliable information about the structures. (C) 2004 Elsevier B.V. All rights reserved.