原子力显微镜对液晶显示器件基板表面结构的研究  

AN INVESTIGATION OF SURFACE STRUCTURES OF GLASSES FOR LIQUID-CRYSTALLINE DISPLAY-DEVICES BY AN ATOMIC FORCE MICROSCOPE

作　　者：宣丽[1] 神山勉 川村泰彬 黄锡珉[1] 

机构地区：[1]中国科学院长春物理研究所液晶研究室 [2]日本理化学研究所生物物理研究室

出　　处：《液晶通讯》1993年第1期1-16,共16页

摘　　要：本文通过原子力显微镇观测了附着在ITO玻璃上的液晶取向剂聚乙烯醇膜的表面形貌。同时作为对比实验,观测了ITO玻璃和载玻片的表面形貌。ITO膜层是由直径大约100nm的球形颗粒或无规则颗粒簇组成,聚乙烯醇的构造相对致密,而三者之中载玻片的表面最光滑.将这三种材料表面分别作轻重摩擦两种处理,重新用原子力显微镜观察.轻摩擦者看不到任何摩擦痕迹,唯有重摩擦过的聚乙烯醇表面和载玻片表面,出现摩擦沟痕.ITO表面由于硬度高且粗糙,没有观测到摩擦沟痕。将表面摩擦过的各种材料基板作夹心式液晶盒。在偏光显微镜下观察,向列相液晶5CB(pentycyanobiphenyl)均能很好地定向排列,显现平行排列的单畴图象。说明:a、100nm左右的粗糙程度不破坏5CB这样分子尺寸的液晶排列;b、分子尺寸的摩擦痕迹在液晶排列过程中起到关键作用;c、由于实验用的基板表面是由不同材料构成,且摩擦后均使5CB液晶取向排列,所以排列机理应与表面分子结构无关。Microstructures of surfaces of ITO-coated glass plates with and without a polymer film on the surface were observed by an atomic force microscope (AFM). The polymer used was polyvinyl alcohol (PVA) with degree of polymerization 2000 or 500. The surface of a conventional cover glass was also observed by AFM for a comparison. The observed ITO surface was constructed from 'cocoon' shaped particles sized about 100nm in diameter. Wherease the surface of cover glass was rather smooth. Thte roughness of PVA surface lay middle between the two. The morphology of PVA film on the surface of ITO-coated glass seems not to be affected by the roughness of the underlying ITO surface, which means that the thickness of PVA film is large enough to form its own surface structure. The three surfaces were rubbed by a patch of clothe, and observed by AFM again. The grooves about 4nm deep on the surface of PVA film and some scratches on the surface of cover glass were observed when the rubbing was strong, and rubbing traces could not be observed when the rubbing was weak. No trace of the rubbing was found on surfaces of ITO-coated glass whether the rubbing was strong or weak. However, all of these rubbed surfaces gave a good molecular alignment to a nematic liquid crystal, pentylcyanobiphenyl (5CB), confined in a sandwich cell made by them. Under a polarizing microscope, the image of the cells was a single domain homogeneous one. The experimental results indicate that: a ) the roughness around 100nm in diameter does not destroy the alignment of liquid crystal with a molecular size comparable to 5CB; b) a rubbing trace of molecular scale plays a crucial role in the alignment process of liquid crystals; c) since surfaces of different materials with rubbing can align liquid crystals, the liquid crystal aligning mechanism can not be directly related to the molecular structure of surface.

关 键 词：液晶显示器 表面结构 原子力显微镜 

分 类 号：TN141.9[电子电信—物理电子学]