Changes in electrical properties and conduction mechanisms of Pd/n-Si diodes due to niobium dopant

Abstract

A change in electrical properties of silicon (Si) diodes due to niobium (Nb) doping was studied using current–voltage (I-V) and capacitance–voltage (C-V) techniques. The observed ohmic I-V behaviour and a low-voltage capacitance peak on Nb-doped Si diodes indicated that a charge distribution mechanism has been changed and dominated by generation-recombination defect centres in the material. These Nb-induced defect centres are responsible for a reduction in free majority carrier density in the space charge region as a result of charge compensation hence an increase in material resistivity. An increase in material resistivity is confirmed by relatively high series and shunt resistances evaluated on Nb-doped Si diodes. Furthermore, the effects of Nb doping on other diode parameters such as the saturation current, Schottky barrier height, ideality factor and doping density were investigated in the study. Since the observed diode property changes are similar to those induced by promising dopants for silicon radiation-hardness, the results presented here would, therefore, assist in a quest to improve radiation-hardness of silicon by defect-engineering strategy.