The Effect of Field Emission on the Behaviour of Semiconductor Contacts

If the potential applied across a contact between two conducting bodies exceeds one or two volts it is likely that the current flowing will be augmented by field emission around the area of intimate contact. This condition is analysed for conductors with no surface barrier, by treating the relation between surface field and emitted current density as a step-function and solving Laplace's equation with this boundary condition. With contacting bodies of normal shape it is found that the current will vary as the square or three-halves power of the applied voltage. Some experimental observations on semiconductors with negligible barrier effects are shown to be consistent with the predictions of this analysis. A similar analysis can be applied to metallic bodies which are not quite in contact, and shows that the emitted current is so concentrated as to cause melting of the metal even at very low currents.