Defect evolution in proton-irradiated 4H-SiC

4H silicon carbide (4H-SiC) is a critical material for power electronics used in extreme radiation environments such as spacecraft and nuclear reactors. Among all kinds of radiations, proton radiation needs to be well investigated since defects induced by proton irradiation seriously impact device reliability. Crucially, this work uniquely investigates the impact of irradiation direction and energy by exposing 4H-SiC Schottky barrier diodes (SBDs) to proton radiation at five distinct energies with the same dose from both the front and back sides to systematically study energy-and-direction dependent defect formation. Combining high-sensitivity deep-level transient spectroscopy (DLTS) with Monte Carlo-based SRIM simulations, we achieve precise spatial correlation between experimental calculated defect profiles and theoretical displacement damage models. It is found that lower-energy protons tend to generate a higher density of defects in the depletion region. Notably, backside irradiation with 8.5 MeV protons results in a significantly larger defect concentration within the depletion region compared to front-side irradiation with the same energy, highlighting the directional sensitivity of irradiation-induced defects. Finally, the effects of both low-temperature and high-temperature annealing on radiation-induced defects are investigated.