Gallium self-diffusion in gallium phosphide

Ga self-diffusion in gallium phosphide (GaP) is measured directly in isotopically controlled GaP heterostructures. Secondary ion mass spectroscopy (SIMS) is used to monitor intermixing of Ga-69 and Ga-71 between isotopically pure GaP epilayers which are grown by molecular beam epitaxy (MBE) on GaP substrates. The Ga self-diffusion coefficient in undoped GaP is determined to be D=2.0 cm(2) s(-1) exp(-4.5 eV/k(B)T) between 1000 and 1190 degrees C under phosphorus-rich condition. The self-diffusion entropy is found to be similar to 4 k(B). (C) 1997 American Institute of Physics.