L. Thermal acceptors in germanium

Summary Some results previously reported by the author are examined on the assumption that the thermal acceptors are copper atoms. A thermo-dynamic treatment of the solid solubility of copper in germanium is given in terms of the Principle of Lowest Free Energy, enabling a physical picture of the solubility to be given. This explains the approximately exponential dependence on inverse absolute temperature (below 800°c), which formerly led to the belief that thermal acceptors were lattice defects. An equation is derived which relates the concentrations of copper on the liquidus and solidus to the temperature. The experimental results are shown to obey this equation, which is equivalent to the one previously derived by Thurmond and Struthers, using a different approach.