Typical equations and methods used for years to analyse a p-n junction assume planar junction, so measured values are often treated just as volume values. Current components of I-V characteristics are sometimes extracted and analysed separately to determine their own parameters. However capacitance values from measured C-V characteristics are usually taken just as planar values and no extraction is done, The influence of combined capacitance and current components separation on p-n junction parameters and importance of capacitance components separation for accurate analyse of diode is shown for typical physical parameters used to characterise a p-n junction.