Junctions with copper electrodes demonstrate tunneling properties that are intermediate between those with gold electrodes and those with silver electrodes. Whereas φ b of a junction with copper electrodes is similar to that of the corresponding junction with silver electrodes, its a is similar to that of the corresponding junction with gold electrodes. This combination leads to conductance values close to but slightly greater than that of corresponding junctions with silver electrodes due to shorter tunneling distances in copper-based junctions.