DEPOSITION OF METASTABLE THIN FILM MATERIALS BY LIGHT-ASSISTED METALORGANIC CHEMICAL VAPOR DEPOSITION

IT IS PLANNED TO GROW METASTABLE SEMICONDUCTING PHASES, INCLUDING ALPHA-TIN AND CUBIC TIN-GERMANIUM ALLOYS BY LIGHT-ASSISTED METALORGANIC CHEMICAL VAPOR DEPOSITION. PRECURSORS SUCH AS TETRAMETHYL TIN, GERMANE, OR TETRAMETHYL GERMANIUM WILL BE INTRODUCED INTO A REACTOR. AS THE GASES FLOW PAST THE SUBSTRATE, ULTRAVIOLET LIGHT WILL ILLUMINATE THEM THROUGH A QUARTZ WINDOW, AND THE PHOTOLYSIS WILL GENERATE FREE RADICALS THAT WILL DEPOSIT ON THE SUBSTRATE. THE USE OF LIGHT TO DISSOCIATE THE GAS MOLECULES WILL ALLOW EPITAXY TO BE CARRIED OUT AT A LOWER TEMPERATURE THAN WOULD NORMALLY BE THE CASE FOR CHEMICAL VAPOR DEPOSITION. THIS LOWER TEMPERATURE MAY BE CRUCIAL FOR MAINTAINING METASTABLE MATERIALS IN THE DESIRED PHASES. IN PHASE I, THE PHOTOLYSIS OF VARIOUS METALORGANIC COMPOUNDSWILL BE INVESTIGATED TO ESTABLISH THE FEASIBILITY OF THE PROCESS. THE INFLUENCE OF LIGHT INTENSITY, SUBSTRATE TEMPERATURE, AND OTHER VARIABLES WILL BE ESTABLISHED. IF PHOTOLYSIS AND DEPOSITION OF METALS FROM THESE COMPOUNDS IS SUCCESSFUL, PHASE II WILL BE CONCERNED WITH ESTABLISHING THE CONDITIONS NEEDED FOR EPITAXIAL GROWTH.