In order to make an accurate determination of Schottky diode parameters such as the ideality factor, the barrier height and the series resistance [using forward current-voltage (I-V) characteristics in the presence of an interfacial layer], a novel calculation method has been developed by taking into account the applied voltage drop across the interfacial layer (V-i). The parameters obtained by accounting for the voltage drop V,have been compared with those obtained without considering the above voltage drop. To examine the consistency of this approach, the comparison has been made by means of Schottky diodes fabricated on a n-type semiconductor substrate with different bulk thickness. It is shown that the voltage drop across the interfacial layer will increase the ideality factor and the voltage dependence of the I-V characteristics. In addition, it is shown that the series resistance value increases as the semiconductor bulk thickness has been increased.