Orientation of nematic 5cb and photo capacitive properties of si/nematic/ito structure with a-si

The orientation of nematic 5СВ on films of amorphous silicon (a-Si) obtained by the magnetron method and photo-capacitive properties of the Si/nematic/ITO structure, as a prototype of an optically addressed liquid-crystal light modulator, is investigated experimentally by its photoexcitation by focused laser radiation (He-Ne 0.6 $\mu$m). It has been shown that the orientation of the nematic 5СВ is obtained homeotropic on a-Si films deposited both on the surface of single-crystalline silicon and on the surface of silicon oxide. It was established that during the magnetron sputtering of a-Si, ZnO, Si3N4 films using masks made of both silicon and metal, a uniform planar orientation of the nematic is formed in the form of a strip for some depth from the mask edge on that part of the substrate surface, which during thedeposition was masked. It is assumed that the planar orientation of the nematic is formed on the film that was obtained by deposition of the material at an oblique angle into the microgap between the substrate and the mask. The voltage drop method allows to investigate: (1) the formation of silicon surface depletion, (2) the effect on the surface depletion of a constant bias and frequency of the control voltage, as well as the presence of a-Si nanoscale film on silicon surface, while testing voltage, in contrast to bridge methods, may be in a wide range of values, including the voltage corresponding to the Fredericks threshold. An interpretation is given of the separation of the dependences of the voltage drop on frequency into two ranges: low frequency and high frequency, respectively, which is associated with the transfer and accumulation of ionic charges in a layer of liquid crystal. The agreement of the results of experiments on the method of photosensitivity disappearance threshold, in which the visual reaction of the liquid crystal layer to the irradiation of the structure with active light are recorded and the results by the method of voltage drop is shown.