Passivation of silicon surface by ultrathin dielectric film in M/Si/nematic/ITO structures

In this work the experimental observation of passivation of silicon surface by ultrathin dielectric film in Al/Si/nematic/Indium Tin Oxide(ITO) structure performed on the base of low resistive (~ several Ωxcm) n-type conductivity silicon sample is presented. It is shown that when the DC voltage with polarity +U on silicon is applied to the structure a passivation effect of silicon surface takes place. It is found that a silicon surface passivated by dielectric film changes an initial alignment of liquid crystal 5CB. In the structure with passivating silicon surface a frequency range of structure photosensitivity extends due to limitation of current leakage through Si/liquid crystal interface. Keywords: nematic, silicon, passivation, alignment, photosensitivity, light modulator

Micropatterning in bistable cholesteric device with Bragg's reflection

In this work, the method to form bistable patterning in a cholesteric cell with Bragg’s reflection in the visible spectral range is demonstrated. In order to reach this, we used a Si/SiO₂ structure in which a potential relief on SiO₂ surface is induced due to enrichment and depletion of required form areas of the silicon near-surface layer during external electric field action. The patterning of enrichment is determined by the positive charge embedded into SiO₂ film, which is formed by thermodiffusion of aluminum atoms

Ion induced field effect in silicon in nematic liquid crystal cell

An influence of ion charge on surface conductivity of silicon in In₂O₃/5CB/monocrystal silicon/Al structure, in which a specific resistance of silicon is much less than a specific resistance of liquid crystal layer, was studied. Within the frequency range of 103-106 Hz of external voltage, a depletion state in silicon has been observed. We found that the field effect in silicon is induced by ion charges localized near silicon surface. It is shown that method based on visualization of n+ pockets on n-Si substrate by liquid crystal enables to estimate the impurity ion density near silicon surface. Analysis of the field effect induced by polarized charges formed by the prior action of DC voltage has allowed us to conclude that: 1) up to several volts of DC, a charge injection from silicon surface into liquid crystal is absent; 2) ion charge accumulated near silicon surface is partially adsorbed on silicon surface; 3) high voltage with "+" U polarity on silicon causes full absence of photosensitivity. We demonstrated that such type of structure could be used as liquid crystal spatial light modulator

Electron beam micropatterning in liquid crystal cell by using nano-scale carbon containing films

We demonstrate experimentally, that hydrocarbon (CH) films obtained as result of snuff effect in a residual atmosphere of electron scanning microscope under electron beam on amorphous SiO₂ surface possess useful properties for microdevices creation, namely: 1) micropattern of CH film is determined by electron beam raster, 2) locally suited axial-symmetric CH films can be obtained by no moving electron beam, 3) thickness of CH film influences on liquid crystal orientation, 4) take place the influence of electron beam movement features on orientation of liquid crystal, 5) CH films demonstrate bistable behavior of nematic