Picosecond photodetectors fabricated in GaAs layers grown on silicon and silicon-on sapphire substrates

Response times of ∼40 and 60 ps (FWHM), respectively, have been measured for photoconductive detectors fabricated in GaAs layers grown by molecular beam epitaxy on silicon substrates and on silicon-on-sapphire substrates, These devices are the first reported high-speed photodetectors in the monolithic GaAs/Si material system and the first reported electronic or optoelectronic devices of any kind in the monolithic GaAs/silicon-on-sapphire system.