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The energy dependence of the ionization produced in germanium by energetic germanium atoms was measured. Germanium solid-state detectors served simultaneously as crystalline Ge sample, neutron target, and ionization detector. The spectrum of ionization produced by prompt Ge recoil atoms energized by monoenergetic neutron bombardment was observed in a pulse-height analyzer, and the edge of the spectrum was identified with the ionization produced by Ge recoil atoms having the calculated maximum recoil energy. The electron-hole pair production of Ge recoils was measured in this manner from 21.4 to 997 keV, using monoenergetic neutrons from 400 keV to 18.6 MeV. In this energy range, the ratio of the ionization produced by a Ge recoil relative to that of an electron of the same energy increased from ~0.15 to ^0.7. At very low Ge recoil energies, most of the energy goes into atomic processes. At high recoil energies, where electronic processes become important, the ionization produced by a Ge recoil appears to approach that for an electron of the same energy. The corresponding partition of energy between electronic processes and atomic processes for an energetic Ge atom in a Ge lattice agrees favorably with predictions of the theory of Lindhard et al. These data together with the earlier results of ionization produced by energetic Si atoms within a Si lattice agree with the A and Z dependence of the partition of energy predicted by Lindhard.

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Measurements of the change In low-temperature thermal conductivity of high-purity single-crystal Ge were made upon 2-MeV electron irradiation and annealing. Strong scattering of phonons by small concentrations of radiation-induced defects is observed. The additive thermal resistivity increases as the 0.58 power of the time integrated flux 3> rather than the first power observed for GaAs. Irradiation to 3.4X10 18 2-MeV e/cm 2 below 50°K gave 1/K-1/JTo-1.7XlO" 11^5 * cm-deg/W at 20°K. For between 10* and 10" 2-MeV e/cm 2 , the magnitude of the increase in thermal resistivity of Ge is comparable to that observed for GaAs even though the lattice strain is much smaller. Strain and mass-difference scattering theories cannot explain the Ge data as they can the GaAs data. The Keyes or Pyle phonon-electron scattering theories, however, can explain the Ge results. A small amount of annealing of the additive thermal resistivity was observed to begin at 35°K in the high-purity Ge studied here. This is in agreement with the first annealing stage seen by electrical measurements in degenerate n-type Ge by MacKay and Klontz and in degenerate _^-type Ge by Gobeli. Large recovery states are seen at 125 and 200°K. In the annealing-temperature interval between 140 and 200 °K, the thermal conductivity is strongly dependent on electron trapping and can be significantly decreased by a short illumination which changes the charge states of the defects. This demonstrates the phonon-electron scattering nature of the thermal resistivity. Measurements of the temperature dependence of the thermal conductivity indicate that the defects anneal as point defects. The large precipitation of point defects seen in GaAs is not seen in Ge, and almost complete recovery of the radiation-induced defects occurs by 405°K. Minima are observed in the temperature dependence of the thermal conductivity, suggesting localized mode scattering.

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 1/K-1/K Q = (3.15±0.2) X 10~1 9 cm-deg/Wper 2-MeV electron/cm 2 . The experimental ratio of the point-defect thermal resistivity to the induced lattice strain at 50°K is (1/K-l/Ko)/ (3AL/L) = (1.0 ±0.2) X10 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 1/K-1/K 0 = (94±10)X10 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.

The production of divacancies in Si by 400-keV oxygen ion implantation (ΦI = 1.75 × 1014 cm−2, two sides) was detected by the characteristic divacancy optical absorption band at 1.8 μ. This band has been previously correlated with the presence of divacancies in electron- and neutron-irradiated silicon. Ion-produced divacancy annealing near 200°C was observed to correlate with neutron-produced divacancy annealing. Detailed comparisons of the annealing of electron-, neutron-, and ion-produced divacancies suggest that the ion-produced divacancies anneal primarily in regions with sink concentrations ≥ 1019 cm−3.