We have prepared small Au/n-GaAs Schottky barrier diodes (SBDs) using e-beam lithography (EBL), and obtained their effective barrier heights (BHs) and ideality factors from current-voltage (I/V) characteristics, which were measured using a conducting probe atomic force microscope (CP-AFM). Although the diodes were all identically prepared, there was a diode-to-diode variation: the effective BHs ranged from 0.795 eV to 0.836 eV, and the ideality factor from 1.025 to 1.101. Lateral homogeneous BHs were computed from the observed linear correlation between BH and ideality factor using the method of Schmitsdorf et al. [Schmitsdorf RF, Kampen TU, Monch W. J Vac Sci Technol B 1997;15(4):1221]. These homogeneous BHs were also obtained from the fit to the experimental I/V characteristics of the current through a "patchy" diode. From our model, the barrier height in the patches and their diameter could be determined. It are however the homogeneous BHs which should be used to make theories of the physical mechanisms responsible for the Schottky barrier height of the metal-semiconductor combination considered. (c) 2005 Elsevier Ltd. All rights reserved.