Research On The Radiation Effect Of Power Field Effect Transistor

Power semiconductor can be degraded and damaged in radiation environment.It threats the safety of equipment using these devices or even the whole system.Field Effect Transistors(FET)are the most commonly used power semiconductor devices,which include power MOSFETs and GaN HEMTs.Different particles in radiation environment can induce various radiation effects.The most important radiation effects include: total ionizing dose(TID)effects and single event effects(SEE)in power MOSFETs,as well as proton irradiation effects in GaN HEMTs.These effects are investigated by using experiment,simulation and modeling methods in this dissertation.For VDMOS of power MOSFETs,the research is focused on radiation hardening for TID and single event burnout(SEB).After TCAD simulating,layout and fabrication,TID hardened demo devices are developed.The experiment results show that the devices are able to resist 200 krad(Si)TID.A new method to mitigate SEB effects is also proposed.This method increases the channel doping and replaces gate oxide by high-k dielectrics in VDMOS.Simulation results from a calibrated structure demonstrate that this method indeed can mitigate the SEB effects.For the single event micro-dose effects in trench MOSFETs,a single ion charge deposition model in oxide is developed.The sensitive parameters in micro-dose effects are investigated by using this model and Sentaurus TCAD software together.To investigate proton irradiation effects in Ga N HEMTs,enhancement mode Ga N HEMTs are irradiated,both destructive damage and parameter degradation are observed.By analysis the experiment results,the destructive damage is attribute to the proton induced anomalous large gate current,which leading to destroy the Al Ga N barrier layer.The float-end capacitance measurement and Sentaurus simulation indicate that proton induced deep level traps in Al Ga N barrier/p Ga N cap interface are the main reason of parameter degradation.