Effect of proton fluence on point defect formation in epitaxial silicon for radiation detectors

High-resolution photoinduced transient spectroscopy (HRPITS) has been used to investigate defect centres in n-type epitaxial silicon after 24 GeV/c proton irradiation with fluences of 3×1014 and 9×1014 cm−2 followed by a long-term annealing at 80 oC. The measurements revealed nine traps with activation energies ranging from 5 to 460 meV. In the material irradiated with the lower fluence the concentration of V2O−/0 complexes is found to be approximately 4 times lower than that of divacancies V2−/0. After the irradiation with the higher fluence the material defect structure is different and the concentration of V2O−/0 complexes is around 6 times higher compared to that of divacancies V2−/0.