Capacitance–voltage behaviour of Schottky diodes fabricated on p-type silicon for radiation-hard detectors

Capacitance–voltage measurements were carried out on Schottky diodes fabricated on undoped and on metal-doped p-type silicon. The metals used are gold, platinum, erbium and niobium. The obtained results were used to investigate the effects of the metals on the silicon material by inference from the electrical properties of the diodes. The data were used to extract the doping density of the material and the Schottky barrier height of the device. The results show that gold, platinum and niobium all reduce the doping density while erbium increases it. A reduction of the doping density shows that the resistivity has increased. This increase of the resistivity is caused by defects that are created by the metals in the energy gap of silicon. The defects compensate charge carriers to turn the silicon into a relaxation material. Devices fabricated from relaxation material have been found to perform better as radiation-hard detectors. The Schottky barrier height is independent of the doping density to show that it is not a bulk material property.