Silicon diodes fabricated on defect-engeneered material for use as radiation detector

Abstract

Current-voltage and capacitance-voltage measurements have been carried out on uradiated commercially available silicon p-i-n photodiodes under illumination of different wavelengths. The photodiodes were irradiated by 1 Me V neutrons at different fluences. A main indication is that effects due to incident photons are more pronounced at low radiation fluence but they become negligible as the fluence increases. These results show that silicon gets quickly damaged by radiation in the initial stages of the irradiation process but as the fluence increases the material becomes resistant to further damage. The measurements were also carried out on Schottky diodes fabricated on metal-doped silicon. The metals used were gold, platinum, erbium and niobium. Using the Rutherford Backscattering Spectroscopy and X-ray Photoelectron Spectroscopy techniques, they were found to diffuse into silicon at the annealing temperature of 900 °C and a time of 18 hours. The overall results indicate that doping with metals is similar to the irradiation. Their effects on the material reduce the conductivity and change the behaviour of the diodes from the normal exponential behaviour to the Ohmic behaviour. These two features show that irradiated or metal-doped silicon is a relaxation material. This type of material is radiation-hard since the effects of radiation on it have been found to be suppressed.