Ionic field effect in epitaxial AgBr layers

Abstract

Reversible variations in the conductance of thin AgBr layers due to a capacitively applied electric field normal to the surface are measured. A suitable etching of the layers is made leading to changes in surface properties and to the appearance of the field‐effect signal. The effect of etching is discussed in terms of a healing of the surface disorder. The classical semiconductor physics theory of Garrett and Brattain is adapted to describe the surface conductance vs. surface potential dependence in silver halides. Observation of a minimum in the conductance curve makes possible the calculation of the surface potential and the charge in surface states. The results obtained support the model of Poeppel and Blakely indicating a finite number of surface sites.