Measurements of interface recombination velocity by capacitance/collection efficiency variation in Cu2S/CdS heterojunctions

The interface recombination velocity S/sub I/ in the Cu2S/CdS heterojunction has been measured by a new technique using junction capacitance and collection efficiency. The method capitalizes on changes in the junction field strength due to the photocharging of traps in the depletion region, as measured by junction capacitance. The variation in junction collection efficiency is related to the field strength changes to obtain S/sub I/ values of order approx.3 x 105 cm/s. These compare well with estimates from other experiments and simple theoretical predictions. This measurement technique could be applied to other systems, so long as photosensitive trapping states exist that alter the depletion layer width upon external illumination