Recombination diffusion length of minority charge carriers in cuprous sulphide (chalcosite and djurleite)

We have determined the recombination diffusion length of minority charge carriers in thin single crystals of chalcosite and djurleite prepared from crystals of CdS with the c-axis in-plane. The recombination diffusion lengths were determined from the photovoltage developing in a small CdS crystal pressed against one side of the crystals as a function of the penetration depth of the light incident on the other side. In interpreting the data various complications were taken into account, such as reflections of the light and absorption by free carriers. For chalcosite in equilibrium with djurleite a value of 300 to 350 Å was found; in djurleite the distance between the site of generation and recombination is smaller than 50 Å.