We have fabricated Au/n-GaAs Schottky barrier diodes with different surface treatments. Prior to Au evaporation on the n-GaAs(100), the first kind of samples has consisted of dip in the 5H(2)SO(4)+H(2)O2+H2O solution and then H2O+HCI solution, followed by a rinse in de-ionized water (,sample AuG1), the second kind of sample has consisted of several steps of anodization in aqueous 4C(2)H(6)O(2) + 2H(2)O + 0.1H(3)PO(4) electrolyte with pH = 2.02 each followed by a dip in diluted aqueous HCl solution and a subsequent rinse in de-ionized water (sample AuG2), and the third kind of samples one anodization step only (MIS sample AuG3). We have found the lowest values of both the barrier heights and ideality factors for the reference sample AuG1. The anodization, on the other hand, has increased the barrier heights as well as the ideality factors. Furthermore, the barrier heights of approximately 0.80, 0.90, and 1.01 eV for the AuG1, AuG2, and AuG3 diodes, respectively, have been obtained adding the contribution due to image force effect. (C) 2002 American Vacuum Society.