The University of British Columbia

The temperature dependence of the diffusion of lead in GaAs is determined by measuring the modification to the energy spectrum of emitted alpha particles from the decay chain of implanted Pb-212 atoms. Diffusion rates are measured for temperatures up to 900 degrees C. Higher rates are observed for the diffusion in silicon-doped GaAs than in semi-insulating GaAs. An upper limit for the diffusion of radium in GaAs is similarly obtained from the decay of the Ra-224 isotope. Implications for the use of implanted alpha sources for thickness monitoring during epitaxial film growth by the alpha-particle energy loss method are discussed. (C) 1998 American Institute of Physics. [S0021-8979(98)07123-0]