Title :
Characterization of Semi-Insulating 4H Silicon Carbide for Radiation Detectors
Author :
Mandal, Krishna C. ; Krishna, Ramesh M. ; Muzykov, Peter G. ; Das, Sandip ; Sudarshan, Tangali S.
Author_Institution :
Electr. Eng. Dept., Univ. of South Carolina, Columbia, SC, USA
Abstract :
Radiation detectors have been fabricated on 8 mm × 8 mm substrates, ~390 μm in thickness, diced from a (0001) 4H-SiC semi-insulating (SI) wafer (≥ 1012 Ohm-cm). The crystals used for detector fabrication have been characterized by x-ray diffraction (XRD), electron beam induced current (EBIC), chemical etching, cross-polarized imaging, and Raman spectroscopy. Current-voltage (I-V) characteristics showed very low leakage current (≤ 50 pA at -800 V) and the capability of detector´s operation ≥ 470 K. EBIC investigations revealed that the screw dislocations produce dark EBIC contrast indicating high leakage current in the defective regions. 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 ~460 K associated with the ~1.2 eV center was much stronger than the other high temperature peaks (e.g., 370 K due to vanadium impurity, 0.95 eV below of conduction band edge), indicating that this level along with the 1.56 eV level should dominate in controlling the resistivity and carrier lifetime in the studied 4H-SiC. Based on the literature data, we associate these centers with intrinsic defects and/or V-related complex. Nuclear detection measurements on the single-element SiC detectors with 241Am X-γ ray source clearly detected 59.6 keV and other low energy x-rays.
Keywords :
EBIC; X-ray detection; X-ray diffraction; etching; gamma-ray detection; silicon radiation detectors; temperature measurement; 4H-SiC semiinsulating wafer; 241Am; Raman spectroscopy; TSC measurement; V-related complex; X-gamma ray source; X-ray diffraction; XRD; carrier lifetime; chemical etching; cross-polarized imaging; dark EBIC contrast; defective region; detector fabrication; electron beam induced current; electron volt energy 1.1 eV to 1.2 eV; electron volt energy 1.56 eV; electron volt energy 59.6 keV; high temperature resistivity measurement; nuclear detection measurement; radiation detectors; screw dislocation; semiinsulating 4H silicon carbide; single-element SiC detectors; substrates; temperature 460 K; thermally stimulated current; vanadium impurity; very low leakage current; Detectors; Electron traps; Fasteners; Radiation detectors; Silicon carbide; Substrates; Temperature measurement; Defects; electron beam induced current; radiation detectors; semi-insulating; silicon carbide; thermally stimulated current;
Journal_Title :
Nuclear Science, IEEE Transactions on
DOI :
10.1109/TNS.2011.2152857