Other Models of Charge Generation and Transport

The transport mechanism of the slow photoconductivity is determined by the hopping process. In the oriented samples it was observed as a strongly anisotropic mobility of the carriers with respect to the applied electric field (flll/flx = 50). The amplitude of the photoconductivity signal was also anisotropic with respect to the polarization of the incident light. For these reasons, 

Some difficulties of the soliton theory for explanation of the photovoltaic and other effects were also noted [124-127]. 

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