The impression of series resistance on unipolar semiconductor device's capacitance-voltage spectrum is discussed by conventional impedance and admittance analysis, and it is shown that series resistance may cause large errors in capacitance-voltage data. It is shown that the existence of such errors can be deduced from suitable complex impedance measurement obtained during the capacitance-voltage measurement process and this information can be used to correct the distorted capacitance values. A theoretical analysis and computer simulation are presented in order to illustrate the nature of the problem and the technique by which accurate depletion region capacitance can be obtained. (C) 2008 Elsevier Ltd. All rights reserved.