Photoconductivity of microcrystalline AgBr : I− emulsions

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Abstract
It is experimentally demonstrated that the photoelectron trap depth of AgBr : I− is unaffected by I− addition. The trap density increases with both I− content and with the size of the crystal. It is likely that the traps are on the surface of the microcrystals. Photoelectron decay data indicate that, after saturation of a few deep traps, the decay rate for temperatures above 60 K is determined by diffusion of interstitial silver ions (Ag+i) to the sites of trapped electrons. The activation energy for Ag+i diffusion in AgBr : I− is higher than in AgBr, and the concentration of Ag+i increases with both crystal size and I− content. These results are explained in terms of a more uniform Ag+i distribution and a probable localization of Ag+i near the I− impurity.