On the role of tunneling in metal-semiconductor nanocontacts

The shape of the contact potential that arises at the interface between semiconductor and a metal nanoparticle is calculated in the approximation of complete depletion. The particle represents a sphere of radius a≪S, where S is the thickness of the depletion layer in the semiconductor in the case of an infinite plane contact with the metal. A WKB approximation is applied to develop a theory of thermal-field current transfer through such a contact. It is shown that, as the radius of the metal nanoparticle decreases, the component of thermal field emission current plays an increasing role in the current transfer, while the backward current density increases and may become comparable to the density of forward current. In this case, the current-voltage characteristics (CVCs) become more symmetric.