Logarithmic Relaxation of the Photoconductivity of a Quasi-One-Dimensional TiS3 Semiconductor

Transient processes in the photoconductivity of TiS₃ single crystals exposed to rectangular light pulses in the wavelength range of λ = 405–940 nm are investigated. It is established that the decay in the photoconductivity after switching the light off at temperatures from 78 to 180 K is described by a logarithmic law in the range from 10^–3 to 10² s (i.e., when time changes by five orders of magnitude). This means that the relaxation process is characterized by times ranging, at least, from several tens of microseconds to several tens of minutes. It is shown that the relaxation is basically successive: the recombination barrier increases while the conductivity approaches the equilibrium value.