Alignment of liquid crystals by ion etched grooved glass surfaces

Abstract

The alignment properies of the nematic liquid crystal (LC) 4'-n-pentyl-4-cyanobiphenyl (5CB) on glass substrates with parallel grooves are studied. The U-shaped grooves with a variety of depths and periods were prepared by the reactive ion etch method. Surface morphology of the grooved glass was, examined by an Atomic Force Microscope. An LC cell consisting of a pair of parallel grooved substrates with 5CB sandwiched in between was assembled. The alignment quality for the LC was studied by measuring its surface azimuthal anchoring strength. The effect of the groove period and depth were studied. Strong anchoring with strengths larger than 10(-5) j/m(2) can be achieved with groove depths of 56 or 121 nm and periods less than 4 mu m.