Effect of Neutron Irradiation on High Voltage 4H-SiC Vertical JFET Characteristics: Characterization and Modeling

The effect of neutron irradiation on commercial vertical high voltage normally-OFF SiC power N-JFETs was investigated. JFETs were irradiated with 1 MeV neutron equivalent fluences up to 4×10¹⁴ cm^-2. Measurement showed that fast neutrons introduce deep levels acting mostly as deep acceptor centers. These centers gradually compensate lightly doped channel and drift regions of JFETs. As a result, characteristics are deteriorated, the JFET threshold voltage gradually increases and transconductance is lowered. At fluences higher than 4×10¹⁴ cm^-2, the low doped n-regions are fully compensated and transistor loses its functionality. The 2D physical model of JFET in ATLAS simulator was developed and calibrated including the neutron irradiation effects. Simulation showed a good agreement with experimental data. This confirmed that carrier removal in the channel and drift region by acceptors centers introduced by neutrons is a dominant reason of SiC JFET degradation.