Electric Tunnel Effect between Dissimilar Electrodes Separated by a Thin Insulating Film

The theory of the electric tunnel effect has been extended to asymmetric junctions—i.e., junctions having electrodes of different materials. It is found that the J—V characteristic is polarity-dependent. At lower voltages, the greater current flows when the electrode of lower work function is positively biased, in agreement with observations on junctions having one aluminum electrode. At higher voltages, there is a change in direction of rectification; i.e., greater current flows when the electrode of lower work function is negatively biased. This effect has also been experimentally observed.