Abweichendes Verhalten der Kapazität von Metall-Kontakten auf reinen Halbleiterspaltflächen gegenüber dem Schottky-Modell

Abstract

A pair of surfaces has been produced by cleavage of a semiconductor crystal, containing the same concentration of donors just below the freshly exposed faces. Two types of experiments have been carried out:

• 1. ZnO crystals were cleaved normal to thec axis in ultrahigh vacuum. The same metal (Au) was evaporated simultaneously on the two polar surfaces.

• 2. Si crystals were cleaved along (111) planes. Two different metals (Au and Cr or Au and Cu) were evaporated on the two identical surfaces.

The differential capacityC of these contacts was measured as a function of bias voltageU. In spite of the equality in donor concentration for the pair of contacts the slope of the plots 1/C ²(U) differed in both types of experiments. This result cannot be explained by Schottky's theory. A paper proposing a model for interpretation of the results is in preparation.