Analysis of turn-on transient in power Bipolar-Mode FET (BMFET)

In this paper the turn-on transient behaviour of a power bipolar-mode JFET (BMFET) is investigated with both resistive and inductive load, by using two-dimensional numerical simulation. It is shown that the BMFET turn-on transient consists of two parts pertaining to the unipolar and to the bipolar modes of operation of the device, the former being much faster than the latter. It is found that the doping of the epitaxial layer plays an important role in the switching performance of the BMFET during the bipolar mode transient, and that a reduction of the resistivity of the epilayer may significantly reduce turn-on losses. It is also shown that the increase of the epilayer doping yields an improved current gain and does not significantly affect the voltage blocking capability of the BMFET.