Electronic bistability in an electrochemically self-assembled array of semiconductor quantum dots

A novel electronic bistability has been observed in a two-dimensional array of electrochemically self-assembled CdS quantum dots dispersed in alumina. The dots are produced by electrodepositing CdS in 100 Angstrom-sized self-organized pores in a nanoporous alumina film produced by the anodization of an aluminum foil in sulfuric acid. The current-voltage characteristic of the array shows two distinct conductance states. The system switches from one conductance state to another if the de bias is taken past a threshold voltage. This bistable behavior is perfectly repeatable. If the system is left in one conductance state, it remains there indefinitely until switched to the other state by the application of an external de bias. A speculative model is proposed which may explain this behavior. Such an effect may find applications in extremely dense static random access memory.