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The diffusivity and solubility of Cu in Ge have been investigated as a function of temperature in the temperature range 700°-900°C, both by resistivity and radio-activity methods. The average diffusivity is 2.8±0.3X10~5 cm 2 /sec in this temperature interval. The solubility shows a maximum of 4.0X10 16 atoms of copper cm -3 at about 875°C. The precision is not sufficient to determine an activation energy for diffusion. However, calculations based upon a theory of Wert and Zener, indicate an activation energy of about 4000 cal. The "thermal conversion" effect in Ge is explained by a temperature-dependent solution and precipitation of Cu. It is suggested that the acceptor and diffusional properties of Cu in Ge can be accounted for by decreased electron affinity of Cu at higher temperatures.

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The resistivity and Hall coefficient RH for Zn-doped GaP were measured at temperatures between 4.2° and 775°K. Neutron activation and through diffusion with radioactive 65Zn were used to determine the Zn concentration NZn, which ranged from 6.7×1016 cm−3 to 2.1×1019 cm−3. At the lowest Zn concentration the thermal ionization energy for Zn in GaP was found to be 0.060±0.002 eV. The thermal ionization energy decreases rapidly for Zn concentrations in excess of 2.0×1017 cm−3. Metallic impurity conduction was observed at a Zn concentration of 2.1×1019 cm−3. The low-concentration region is observed for NZn≲2.0×1017 cm−3, the intermediate-concentration region for 2.0×1017≲NZn≲2.1×1019 cm−3, and the high-concentration region for NZn≳2.1×1019 cm−3. In the intermediate-concentration region the high-temperature hole concentration, determined from p=1/eRH, was found to exceed the Zn concentration by a significant amount. Analysis of the temperature-dependent hole concentration results in an effective density-of-states mass ratio of approximately 0.5. The lightest doped sample had a room-temperature Hall mobility of 120 cm2/V·sec and a maximum mobility of 2050 cm2/V·sec at 55°K. The maximum mobility at low temperature is limited by ionized and neutral impurity scattering, while the dominant high-temperature scattering mechanism appears to be optical phonon scattering.

GaAs doped with ∼1019 cm−3 Se or Te shows reversible temperature-dependent changes in electron (donor) concentration over the temperature range 650 to 1100°C. Crystals containing between 2×1018 cm−3 to approximately 1019 cm−3 donors conform to the same equilibrium curve with an enthalpy of ∼0.5 eV. The behavior is that expected for a solubility equilibrium. Evidence against an equilibrium involving donor precipitation is presented, and the suggestion that the donors may interact to form molecules is discussed.