Recent Progress in Epitaxial Insulators and Metals on Silicon

Epitaxial insulators and metals on Si offer the potential for technological applications. The ability to combine epitaxial metallic, insulating, and semiconducting layers in a heterostructure is an attractive approach to three-dimensional integration. As a step towards achieving this goal, we have used molecular beam epitaxy (MBE) to demonstrate the heteroepitaxial growth of an insulator-metal-semiconductor structure using CaF sub 2, CoSi sub 2, and Si as the metal, insulator, and semiconductor, respectively. The successful growth of this structure requires the use of rapid thermal annealing (RTA) after growth in order to optimize the crystallinity of the layers. In fact, RTA is a technique which is useful for improving heteroepitaxial quality in general, the only major requirement being that the melting point of the substrate must exceed that of the overlayer.