Electrical properties and conduction mechanisms of heavily iron implanted silicon diodes

Abstract

A change in current-voltage (I–V) and capacitance-voltage (C–V) properties of silicon (Si) diodes due to the doping of the material with iron (Fe) is presented. The deviation of diode I–V behaviour from normal exponential to ohmic behaviour indicates that the conduction mechanism is dominated by generation-recombination (g-r) centres after Fe doping. The effects of g-r centres are more pronounced at low-frequency C–V measurements, where the low-mobility minority carriers are active. Due to the recombination of charge carriers, the charge ejection rate out of the space charge region (SCR) is low and less dependent on frequency measurements, possibly, showing that as they dominate the conduction mechanism, g-r centres are stable at one level in the band gap of Si. The results presented here are very important since they explain the properties of g-r centres and they show that in Si, Fe exhibits properties similar to dopants (Au and Pt) found responsible for the improvement of Si radiation-hardness.