Dependence of contact resistivity on impurity concentration in Co/Si systems

Abstract

We have investigated the contact resistivity of Co/Si contact systems with the implantation of B + ions in the doping range from 3×10 14 to 1×10 16 cm −2. The concentrations of electrically activated B atoms are limited by the solubility in Si substrates for the doses above 5×10 15 cm −2 at annealing temperatures of 900–1100°C and the measured contact resistivities are also ruled by those concentrations. The contact resistivities in the high impurity concentration are theoretically calculated based on a tight-binding model in consideration of the formation of impurity bands and band edge tails. The calculated results are in good agreement with the measured values, and a minimum contact resistivity is obtained to be 1.3×10 −7 Ω cm 2 for samples with a dose of 1×10 16 cm −2.