Bipolar Photoeffect Arising from an Anomalous Copper Distribution in and near a Gallium-Diffused Layer in Germanium

A very nonuniform copper distribution occurs in and near a gallium-diffused layer in germanium. This gives rise to a p+-π-p structure, the presence of which has been detected using the sign reversal of the contact photovoltaic effect at wavelength near the absorption edge. Using 64Cu and radiochemical techniques, it has been demonstrated that a high concentration of copper collects in a diffused layer and leads to the observed contact structure.