Nonstationary local reorientation of a nematic liquid crystal in a cell with a silicon $p$–$n$ junction

We report the first observation of the phenomenon of nonstationary local reorientation of a nematic liquid crystal (NLC), which is initiated by a reverse biased $p$–$n$ junction in a cell with silicon substrate. The velocity of reorientation and the distance traveled by a reoriented nematic band (which is tenfold greater than the cell thickness) are determined by the $p$–$n$ junction bias voltage. The band profile depends on the distribution of the surface conductivity, which has been set in this work either by irradiation with 30-keV Ga ions or by light-induced generation of nonequilibriun carriers in silicon. The local reorientation of NLC and the depletion of the silicon surface are explained by the influence of ion space charge in the liquid crystal.