Characterization of 4H Semi-Insulating Silicon Carbide for Radiation Detector Applications

Radiation detectors were fabricated on 8 mm x 8 mm substrates, similar to 390 mu m in thickness, diced from (0001) 4H-SiC semi-insulating (SI) wafer (>= 10(12) Ohm-cm). Our results on characterization including x-ray diffraction (XRD), electron beam induced current (EBIC), chemical etching, cross-polarized imaging, and Raman spectroscopy show the high quality of the SI SiC crystals, which are believed to meet the requirements of fabricating high performance radiation detectors. Current-voltage characteristics showed very low leakage current (similar to 1.5 pA at 500 V) and the capability of detector's operation up to 200 degrees C. Thermally stimulated current (TSC) measurements and high temperature resistivity measurements revealed deep level centers with activation energies 1.1 - 1.2 eV and 1.56 eV. The TSC peak at similar to 460K associated with 1.2 eV center was much stronger than the other high temperature peaks (e. g. 370 K due to vanadium, 0.95 eV), indicating that this level along with 1.56 eV level should dominate in controlling the resistivity and carrier lifetime in the studied 4H SiC. Based on literature data, we associate these centers with intrinsic defects.