DIFFUSION STUDIES OF RA AND PB IN GAAS BY THE ALPHA-PARTICLE ENERGY-LOSS METHOD

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