Low-Temperature Luminescence and Photoconductivity of AgCl

The magnitudes and the decay processes of the luminescence and the photoconductivity of AgCl have been simultaneously investigated between 4°K and 210°K. The decrease of the luminescence intensity with increasing temperature can be attributed to a competing recombination process, not accompanied by visible radiation, and having a thermal activation energy of $E=0.05\mathrm{}$ ev. The decay times are not monotonic functions of temperature, but show maxima. These maxima can be explained in terms of a model in which energy is transported from the site of absorption to the luminescence center by mobile holes and electrons. Delay in this transport is caused by hole and electron trapping, and temperature dependence of the delay determines the temperature dependence of the decay times. Decay curves calculated on the basis of this model are in qualitative agreement with the observed data. The relative magnitudes of the luminescence and photocurrent decay times and the dependence of the decay and rise times on annealing indicate that if the major portion of the photoconductivity is due to electron motion, then luminescence occurs when holes are captured. It is suggested that this recombination occurs at silver ion vacancies.