A novel deposition concept for amorphous superlattices

Cumulative layered structures of amorphous semiconductors have attracted much interest in recent years, as they make it possible to use quantum effects to improve semiconductor properties¹. There is, however, a serious disadvantage in using such superstructures in practical devices, because the conventional process requires mechanical alternation of source gases and evacuation of the system for each layer deposition. As an alternative to this inefficient physically controlled method, we have developed an efficient photochemically controlled method which facilitates the continuous deposition of various superlattices. In combination with two modes of excitation, at least one of which is operated in a pulsed mode, an appropriately selected pair of source gases accumulates continuously binary layers of amorphous semiconductors. As an example of verification of this novel process, an amorphous super-lattice composed of an amorphous silicon carbide barrier layer and an amorphous silicon well layer was prepared from a mixture of disilane and carbon tetrafluoride.