Method of fabricating periodic monolayer semiconductor structures by molecular beam epitaxy

A method of fabricating a composition of matter having a periodic structure of alternating sublattices of GaAs and AlAs comprising the steps of:

• (a) mounting a single crystal substrate in an evacuable chamber,
• (b) reducing the chamber pressure to a subatmospheric level,
• (c) directing a molecular beam of As molecules at a major surface of the substrate,
• (d) during one time period directing at said surface a beam of Ga atoms so as to grow at least one monolayer of Ga on said surface and at least one monolayer of As on said Ga monolayer, thereby forming at least one GaAs monolayer as one sublattice of said structure,
• (e) during a different time period directing a beam of Al atoms at said surface so as to grow at least one monolayer of Al atoms and at least one monolayer of As atoms on said Al monolayer, thereby forming at least one monolayer of AlAs as the other sublattice of said structure,
• (f) controlling the duration of said time periods so that the total number of monolayers of GaAs and AlAs in both sublattices does not exceed four,
• (g) repeating steps (d), (e), and (f) so as to form said periodic structure, and
• (h) during steps (d), (e), (f), and (g) maintaining the temperature of said substrate below a critical temperature in the range of about 610-630 degrees C.