Optical response of switching SmS in thin films prepared by reactive evaporation

We describe a simple technique for fabrication of samarium monosulfide films using reactive evaporation and unheated substrates, resulting in films which consist of highly ordered SmS grains in an amorphous dielectric matrix. Mechanical polishing of the films results in a semiconductor-metal transition in a fraction of the grains, with an associated large change in the optical response. The films are stable in the switched state, and may be locally annealed back to the semiconducting state using a laser, thus suggesting application in optical data storage. The optical properties in both states are successfully modeled using a Bruggeman effective medium theory and experimentally determined values of the input parameters.