Influence of carrier trapping on radiation detection properties in CVD grown 4H-SiC epitaxial layers with varying thickness up to 250 μm

Low doped n-type 4H-SiC epitaxial layers of thickness 50, 150, and 250 mu m grown by hot wall chemical vapor deposition were used to fabricate Ni/4H-SiC Schottky radiation detectors. The epitaxial layers were grown on the (0001) face of highly conductive bulk 4H-SiC substrates 8 degrees offcut towards the (11 (2) over bar0) direction. The 50, 150, and 250 mu m thick epilayer detectors, under optimized settings, showed energy resolutions of 2.0%, 0.78%, and 0.63%, respectively for 5.48 MeV alpha particles. Deep level transient spectroscopy studies showed that the observed variation in the detector resolution is linked to the defect parameters in the devices. Least-squares fitting of the bias dependence of the charge collection efficiency according to a drift-diffusion model, revealed minority carrier diffusion lengths of 16, 10, and 9.2 mu m, respectively, implying that the detectors are not limited by minority carrier trapping. The detector performance was observed to be primarily dependent on the concentration and capture cross-sections of the lifetime killing electron traps Z(1/2) and EH6/7.

Automated summary

Low doped n-type 4H-SiC epitaxial layers were used to fabricate Ni/4H-SiC Schottky radiation detectors, which showed good energy resolutions for alpha particles. The performance of the detectors was mainly determined by the defect parameters in the devices.