Deep level characterization of nitrogen donor traps in 4H-SiC radiation detectors

This article provides a focused study on the charge carrier traps related to the nitrogen donor peak in n -type 4H-SiC devices for radiation detection before and after alpha-particle exposure from Am-241 with fluences up to 10 13 cm −2 . The traps were characterized by comparing current and capacitance measurements using deep level transient spectroscopy (I-DLTS and C-DLTS) alongside thermally stimulated current (TSC) and standard C–V and I–V curves. We report the results from I-DLTS confirm multiple overlapping energy levels around 50 K above freezeout of charge carriers. Most notably, the energy levels around 79, 107, 109, and 124 meV are identified after deconvolution. The 79 meV energy level was identified in the irradiated samples for both C- and I-DLTS measurements, whereas the 107 and 124 meV energy levels were consistent with the C-DLTS measurements. The energy level at 109 meV is identified in both current and capacitance DLTS for the unirradiated reference sample. However, both DLTS methods and TSC measurements indicated that the traps at this energy level were partially deactivated in the irradiated samples, suggesting that the 109 meV energy level is largely correlated with the majority charge carriers from nitrogen doping. These results indicate the susceptibility of 4H-SiC for signal degradation from ionizing radiation when applied to detection and accelerator applications.