Charge-density waves physics revealed by photoconduction

Abstract

The results of photoconduction study of the Peierls conductors are reviewed. The studied materials are quasi-onedimensional conductors with the charge-density wave: K 0.3 MoO 3 , both monoclinic and orthorhombic TaS 3 and also a semiconducting phase of NbS 3 (phase I). Experimental methods, relaxation times, effects of illumination on linear and nonlinear charge transport, the electric-field effect on photoconduction and results of the spectral studies are described. We demonstrate, in particular, that a simple model of modulated energy gap slightly smoothed by fluctuations fits the available spectral data fairly well. The level of the fluctuations is surprisingly small and does not exceed a few percent of the optical energy gap value.