GROWTH AND CHARACTERIZATION OF GAAS SI/GAAS HETEROSTRUCTURES/

GaAs/Si/GaAs heterostructures ranging from similar to 2% of a monolaye r (ML) up to 6 monolayers were grown by molecular beam epitaxy at 500 degrees C, using the dopant furnace for the silicon evaporation. The s amples were characterized by Hall effect measurements, X-ray diffracti on, and secondary ion mass spectroscopy. A reduced carrier concentrati on with doping in the 10(13) cm(-2) region is discussed. A strong decr ease in electron mobility at 1 monolayer is a result of the transition from a doped layer to a GaAs/Si/GaAs heterostructure. The relaxation of the structure is commenced between 3 and 4 monolayers of silicon. S econdary ion mass spectroscopy indicated no or negligible Si diffusion in the strained case up to 3 MLs while a clear peak broadening was se en in the relaxed case.