Low Reverse Recovery Charge 30 V Power MOSFET With Double Epi Structure for DC–DC Converters

Low reverse recovery charge solutions are proposed for 30 V power MOSFETs featuring a double epi structure. The parallel connection of a MOSFET and a Schottky barrier diode (SBD) is used to reduce the recovery charge. The breakdown voltage of the SBD area must be enhanced in order to integrate the MOSFET and the SBD on a single chip. Thus, we studied two types of devices using a double epi structure for enhancing the breakdown voltage of the SBD area. One is an integrated single-chip device and the other is an integrated unit cell device. The integrated unit cell device exhibited lower reverse recovery currents than the integrated single-chip device did during the simulations that were conducted. However, the loss calculation of the integrated unit cell device resulted in an increase in loss because of the diode characteristics needed for the greater barrier height of the p
^-
-layer. Therefore, the integrated single-chip device was experimentally investigated. As a result, the surge voltage of the device was reduced by 58%, which enabled for the use of a lower voltage device and a reduction in the device loss.