Homogeneous liquid crystal molecules on Al₂O₃ alignment films using atomic layer deposition as a function of deposition temperature

In this study, we investigated the orientation characteristics of liquid crystals (LCs) on Al₂O₃ alignment films, which were deposited at three different deposition temperatures by atomic layer deposition (ALD). The deposition temperatures of the ALD process were 100, 200, 300 °C, respectively. To achieve a unidirectional orientation of LC molecules, ion beams were irradiated on the Al₂O₃ alignment films at an ion beam (IB) incident energy of 2400 eV. The orientation of LC molecules within LC cells, fabricated by the Al₂O₃ alignment films deposited at different deposition temperature, indicated the horizontal direction of the atomic-layer-deposited Al₂O₃ alignment films. We confirmed that the LC cells fabricated by Al₂O₃ alignment films deposited at different deposition temperatures had similar electro-optical (EO) performance and pretilt angle characteristics. Through a physicochemical analysis, we found that Al₂O₃ films were unaffected by the deposition temperature, which caused similar LC orientation characteristics. In other words, the fact that Al₂O₃ films deposited by ALD were unaffected by the deposition temperature means that the method using ALD applied on LC alignment films can have a wide deposition temperature range.