Measurements of the change in thermal conductivity of high-purity single-crystal GaAs were made upon 2-MeV electron irradiation and annealing. Two GaAs samples were irradiated at maximum temperatures of 100 and 80°K. A linear increase in the additive thermal resistivity near 50°K is observed upon bombardment. The results yield $\frac{1}{K}-\frac{1}{K_0}=(3.15\mathrm{}\pm 0.2)\times {10}^{-19\mathrm{}}$ cm-deg/W per 2-MeV electron/${\mathrm{cm}}^2$. The experimental ratio of the point-defect thermal resistivity to the induced lattice strain at 50°K is $\frac{(\frac{1}{K}-\frac{1}{K_0})}{\left(\frac{3\Delta L}{L}\right)}=(1.0\mathrm{}\pm 0.2)\times {10}^4$ cm-deg/W. Using estimates for the introduced defect concentration (based upon the change in strain rate as a function of electron energy) together with the observed increase in thermal resistivity, one obtains $\frac{1}{K}-\frac{1}{K_0}=(94\mathrm{}\pm 10)\times {10}^{2}C$ cm-deg/W, where $C$ is the fractional point-defect concentration. This value is intermediate between those predicted by the point-defect scattering theories of Klemens and Ziman. Isochronal anneals carried out above 50°K with all measurements made at 50°K demonstrate low-temperature annealing in GaAs. Annealing is observed to begin near 55°K and accelerate near 190°K. About 70% of the additive thermal resistivity stable at 50°K anneals below 325°K. Definite minima are observed in the temperature dependence of the thermal conductivity, suggesting localized-impurity-mode scattering. The annealing, however, takes place over too large a temperature range to be due to a single thermally activated process. The change in shape of the temperature dependence of the thermal conductivity upon annealing indicates that below 325°K the defects anneal as point defects. For anneal temperatures between 325 and 575°K the point defects no longer remain isolated, and clustering or precipitation is suggested.

• Received 20 March 1964

DOI:https://doi.org/10.1103/PhysRev.135.A1742