Safe hole traps

The trapped holes which recombine slowly because of their low mobility are called safe hole traps . Their presence increases the electron lifetime and the photoconductivity and seems to account for the features of the photoconductivity not explained by the simple model of Eq. (8.69) (McMahon and Crandall 1989). Safe hole traps are most significant in low defect density material, when their concentration can exceed the defect density. A detailed analysis needs to take into account the full distribution of hole traps as well as the dispersive transport of holes. The role of transitions between the band edges in the recombination process also needs to be determined. 

Both reduction centers and latent image centers are composed of silver, and to Moisar "it seems safe to assume that the silver specks formed by reduction are identical to those which somehow appear as subspecks and alleged intermediate entities during photolytic silver formation" (93). He proposed that Ag2 centers formed by exposure by light can act as hole traps and Agj centers act as subdevelopable precursors of latent image centers but, as Hamilton and Baetzold comment (96),... 

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