Exact calculations of the current-voltage curves for N-I-S and S'-I-S junctions with comparison to experimental data

Abstract

The transmission coefficients for the NIS and S'IS sandwich junctions are calculated using the independent electron model approach. The calculated coefficients in both cases are found to be related to the BCS density of state. Since these coefficients appear in the integral expression for the net tunneling current, the tunneling currents for both junctions are also related to these densities of states. The integrals are evaluated numerically to yield a "calculated" net electric current for the two types of junctions. The "calculated" current-voltage curves are in very good agreement with experimental results for junctions containing either conventional superconductors or high-Tcsuperconductors. The only adjustment needed for the curve fitting are the values of the wave vector within the insulator layer in the junction. © 1992.