Study of the annealing effect on silicon microstrip detectors built on [formula omitted] and [formula omitted] substrates after [formula omitted] proton irradiation

Abstract

The behaviour of the leakage current, interstrip resistance and capacitance have been studied on silicon microstrip detectors during an annealing period equivalent to ≃10 8 min at room temperature, after 34 MeV proton irradiation. A comparison between samples of the same geometry built on 〈1 0 0〉 and 〈1 1 1〉 substrates with different resistivity has been carried out. The samples were irradiated at 4 different fluences up to 1×10 14 p/cm 2 . After the irradiation the measurements were performed at room temperature and after heating the samples at 60°C, 80°C and 120°C to cover the complete annealing curve. The leakage current shows the same annealing behaviour typical of a simple diode. The interstrip resistance measured at full depletion voltage ( V dep) decreases in all structures, going down to few tens of MΩ at the highest fluence. It remains practically constant during the annealing period. The interstrip capacitance (at V dep) varies during the annealing period with the same behaviour in both substrates and for all the fluence values: it decreases during the annealing at room temperature, reaching a minimum value, and increases after each heat treatment. Bistable defects seem to contribute to the interstrip capacitance variation.