The electrical structure of crystalline substrates has been studied by a new technique based on selective crystallization of decorating material and selective deposition of charged colloidal particles. Silver chloride was found to be a very effective indicator of the electrical relief of crystal surfaces. At early stages of thermal condensation, it crystallizes orientedly on negatively charged regions of the surface and randomly on those charged positively. The method has been applied to the study of triglycine sulphate, LiF, and NaCl crystals. It has been found that the surface of real crystals consists as a rule of positive and negative regions, representing assemblies of charged point defects. Near the cleavage steps certain "dead zones" arise, in which a local compensation of charges takes place. Nucleation occurs mainly a t charged point defects and oriented coalescence of islands proceeds with different velocity on surface local regions of different signs. The selectivity of crystallization depends on the relation of the sign and magnitude of potential between different smooth areas of the surfaces of crystalline substrates, on the one hand, and between steps and smooth areas, on the other. The charged point defects and their assemblies which are present on the surface of crystalline substrates induce polarization structures of the electret type in amorphous interfacial layers. These structures are "frozen" in interfacial layers in so stable a manner that the layers turn out to be electrical copies of crystal surfaces, thus reflecting the distribution of potential of the surface. Such copies preserve t h e "electrical memory" even after they are detached from the surfaces of crystals and can hence be used as active substrates for various heterogeneous processes, in particular, for epitaxy.
