Hyperbolic decay of photo-created Sb~(2+) ions in Sn_2P_2S 6:Sb crystals detected with electron paramagnetic resonance

摘要

In this paper, we employed a method that overcomes the known limitations of electron paramagnetic resonance (EPR) to monitor charge trap dynamics over a broad temperature range not normally accessible due to the lifetime broadening of the EPR lines at higher temperatures. This was achieved by measuring the decay of the EPR intensity after thermal annealing by rapid cycling back to low temperatures for the EPR measurement. This technique was used to experimentally demonstrate interesting physics in the form of a direct measurement of the hyperbolic decay 1/(1+t) of a charge trap population, which previously was only considered theoretically. The nontrivial effects of bimolecular recombination are demonstrated in the Sn_2S_2P_6:Sb crystals, providing an explanation of the optical sensitization process observed in photorefractive Sn_2P_2S_6:Sb used for dynamic holography.