Achievement

IGERT fellow Darin Leonhardt has worked on a process to produce high quality Ge thin films on silicon substrates. The Ge/Si is a replacement for single crystal Ge substrates that are much more expensive. His growth technique makes use of nanoscale openings on Si to minimize the interfacial strain density and lower the resulting defect density in the Ge film. Over the last year, he developed a process to planarize the Ge film surface to a degree that matches that of commercially available Ge wafers. This method of planarization is based on chemical-mechanical polishing, except that his process is slurry-free and instead relies upon the chemical action of a dilute hydrogen peroxide solution (50 parts DI to 1 part 30 wt% H2O2) and a soft polishing cloth. He has observed room-temperature photoluminescence from GaAs layers grown on our engineered Ge/Si substrates that is comparable to GaAs grown on Ge substrates.