Enhanced Charge Collection in SiC Power MOSFETs Demonstrated by Pulse-Laser Two-Photon Absorption SEE Experiments

A two-photon absorption technique is used to understand the mechanisms of single-event effects in silicon carbide power MOSFETs and power junction barrier Schottky diodes. The MOSFETs and diodes have similar structures enabling identification of effects associated specifically with the parasitic bipolar structure that is present in the MOSFETs, but not the diodes. The collected charge in the diodes varies only with laser depth, whereas it varies with depth and lateral position in the MOSFETs. Optical simulations demonstrate that the variations in collected charge observed are from the semiconductor device structure, and not from metal/passivationinduced reflection. The difference in the spatial dependence of collected charge between the MOSFET and diode is explained by bipolar amplification of the charge carriers in the MOSFETs. TCAD device simulations extend this analysis to heavy ioninduced charge collection. In addition, there is discussion comparing this analysis with experimental results from prior works that show enhanced charge collection resulting from heavy ion irradiation.