Ga self-diffusion in GaAs isotope heterostructures.

Abstract

Isotopically controlled GaAs heterostructures have been used to study Ga self-diffusion with secondary-ion mass spectrometry. This approach probes a close to ideal random walk problem, free from perturbations such as electric fields, mechanical stresses, or chemical potentials. The Ga self-diffusion coefficient in intrinsic GaAs can be well described with $D\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}(43\ifmmode\pm\else\textpm\fi{}25)\mathrm{exp}[(\ensuremath{-}4.24\ifmmode\pm\else\textpm\fi{}0.06\mathrm{eV}){/k}_{B}T]$ over 6 orders of magnitude between 800 and 1225 \ifmmode^\circ\else\textdegree\fi{}C under As-rich condition. No significant doping effects are observed in samples with their substrates doped with Te up to $4\ifmmode\times\else\texttimes\fi{}{10}^{17}{\mathrm{cm}}^{\ensuremath{-}3}$ or Zn up to $1\ifmmode\times\else\texttimes\fi{}{10}^{19}{\mathrm{cm}}^{\ensuremath{-}3}$. Our results substantiate some of the findings in recent theoretical work.