A study on parameters of the Sn/n-GaAs Schottky barrier diode (SBD) fabricated on an n-type GaAs substrate has been made. The Sn/n-GaAs SBD has shown a nearly ideal behaviour with ideality factor and barrier height (BH) values of 1.081 and 0.642 eV, respectively, from the experimental forward-bias current-voltage (I-V) characteristics. A BH value of 0.724 eV has been obtained from the experimental reverse-bias capacitance-voltage (C-V) characteristics. An accurate theoretical modelling of the effect of the presence of inhomogeneities on the electron transport across the metal-semiconductor interface has been applied. This model attempts to explain abnormal experimental results obtained on 'real' Schottky diodes. Our results clearly demonstrate that the electron transport at the metal-semiconductor interface is significantly affected by low-barrier regions (patches). When the experimental data are described by the thermionic emission theory of inhomogeneous Schottky contacts, it has been concluded that both the experimental forward and reverse I-V characteristics and the difference between the values of the experimental I-V and C-V SBHs should be considered. An experimental BH difference of Delta = 0.082 V has been obtained for the Sn/n-GaAs SBD that is less than the critical value; therefore, it has been seen that the potential in front of the patch is not pinched off.