Current-voltage properties of undoped and niobium-doped silicon diodes at different temperatures

Abstract

In this work, Schottky diodes were fabricated on undoped and niobium-doped n-silicon (n-Si). Niobium (Nb) doping was achieved by ion implantation at 160 keV to a fluence of 3 × 1015 ion.cm-2. The diodes were characterized by current-voltage (I-V) techniques at a temperature ranging from 20 K to 360 K in steps of 20 K. A comparison of the change in diode parameters evaluated from undoped and Nb-doped based diodes due to temperature was made to understand the effects of the Nb dopant on the electrical properties of the diodes. In general, the results indicated that the diodes were well fabricated and that Nb doping resulted in an increase in the resistivity of Si. This increase in the resistivity is associated with Nb-induced defects that are responsible for recombination of the mobile charge carrier in Si. A change in I-V graphs from exponential to ohmic behaviour observed at a high temperature range due to Nb doping indicates that in Si, Nb is responsible for the relaxation behaviour of the material. Since the diodes fabricated on relaxation material are radiation-hard, Nb may, therefore, be a suitable dopant in a study to improve the radiation-hardness of Si for current and future use.