Performance evaluation of high-power wide band-gap semiconductor rectifiers

Applicability of GaN in unipolar and bipolar devices for high-power electro nic applications is evaluated with respect to similar devices based on othe r materials. Specific resistance is used as a measure of unipolar performan ce. In order to evaluate bipolar performance, 700 and 6000 V p-i-n diodes b ased on Si, 6H-SiC, and GaN are compared with respect to forward conduction and reverse recovery performance at room temperature and high-temperature conditions. It is shown that GaN is advantageous not only for high voltage unipolar applications, but also for bipolar applications. An empirical clos ed-form expression is presented to predict the avalanche breakdown voltage of wide band-gap semiconductors. Formulation of the expression is based on an approximation of the impact ionization coefficient in terms of seventh p ower of the electric field. (C) 1999 American Institute of Physics. [S0021- 8979(99)06709-2].