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Diodes are the simplest form of semiconductors They consist of two layers a single junction and two terminals The junction is composed from the p type and n type semiconductor and there are also two leads Anode which joins the p type and Cathode which joins the n type The structure of a common diode and its symbol is shown in the Fig below Power diodes are like signal diodes but have some differences in its construction Elbuluk 2010 While the doping level of both P and N sides is same in signal diodes and results in a PN junction power diodes junction is formed between a heavily doped P and a lightly doped N layer which is epitaxial grown on a heavily doped N layer resulting in a structure that looks as shown in the figure below Muller 2003 1 1 2V I Characteristics of Power Diodes Looking at the figure below we can see that the V I characteristics of a power diode is very similar to that of a signal diode For forward biased region in signal diodes the current increases exponentially whereas high forward current in power diodes leads to high ohmic drop which dominates the exponential growth and the curve increases nearly linearly The ultimate reverse voltage that the diode can hold is symbolized by VRRM i e peak reverse repetitive voltage
