Pei-Shiang Chen

Effect of insulating-nanoparticles addition on ion current and voltage-holding ratio in nematic liquid crystal cells

The transient currents induced by an applied direct voltage (dc) electric field have been measured liquid-crystal cells in nematic phase. The experimental results show that the addition of insulating nanoparticles, such as diamond powders, leads to a reduction of the ion concentration in cells so as to drastically reduce the transient currents and threshold voltage. Simultaneously, a high voltage-holding ratio (VHR) in doped cells is observed. Such a high VHR, in comparison with nematic liquid crystals doped by carbon nanotubes, is a superior feature for future liquid crystal display applications.

Effect of Doped Insulating Nanoparticles on the Electro-Optical Characteristics of Nematic Liquid Crystals

Presenting information is essential in many aspects of our daily life. Among all display systems, liquid crystal display (LCD) occupies more than half of the display market as a whole on account of many advantages, including the flat panel, small weight, high definition, small driving voltages, and low power consumption. Currently, almost all LCDs are manufactured with nematic liquid crystal (LC) mixtures. And one of the most common modes for nematic LC displays is twisted nematic (TN) mode. Although the nematic LCs are the dominant materials in display market and for switchable optical devices, the degrading tendency of the performance is undoubtedly a significant barrier for practical applications. The performance of a LC device is mainly affected by the alignment layers and the LC mixtures used. One of the most crucial causes of performance degradation for nearly all the LCDs is the flowing ions within the LC devices. These ions may come from the LCs, the alignment layers, the surrounding glue, be generated by ultraviolet polymerization, or be produced during the filling

Buckled SiGe layers by the oxidation of SiGe on viscous SiO2 layers

SiGe-on-insulator structures have been fabricated by wafer bonding and layer transfer techniques. The relaxation process of the compressively strained SiGe films bonded to SiO2 layers through the rapid thermal oxidation was investigated. Buckling nucleus were randomly located at the beginning of oxidation and the buckling undulation was well developed after 30s oxidation at 960°C. The buckling amplitude increases with the increasing thermal oxidation time. An emission peak at 1.5μm was observed in the low temperature photoluminescence of the buckled SiGe layers.

Recessed Oxynitride Dots on Self-Assembled Ge Quantum Dots Grown by LPD

Recessed oxynitride dots deposited on self-assembled Ge dots are demonstrated using liquid-phase deposition (LPD). By adding ammonia into the solution, the nitrogen atoms can be incorporated into the deposited film. The tensile strain of the Si cap layer directly deposited on Ge dots can enhance the oxynitride nucleation and deposition on Si surface. The tensile strain may also increase the etching rate of the Si cap layer and the recessed dots are formed directly above the Ge dots. The LPD-SiON dots have a higher dot step height as compared to LPD-SiO 2 dots.

Effect of Insulating Nanoparticles Doping on Electro-Optical Characteristics in Nematic Liquid Crystal Cells

The transient currents and the voltage holding ratio (VHR) generated by an applied direct voltage have been measured in nematic liquid crystal (LC) cells. The experimental results show that doping insulating nanoparticles such as ZnO, TiO2 and Si3N4 in nematic LCs leads to a reduction of the moving-ion density in cells and thus drastically reduces the transient currents and threshold voltage. This doping method improves the electro-optical characteristics in nematic LC cells. Moreover, we find that the VHR values are maintained higher than 95% in these doped LC cells. Such a high VHR observed in doped LC cells is a superior feature for future LC display applications.

The Effect of Adding Insulating-Nanoparticles to Nematic Liquid Crystal Cells on Ion Current and Voltage-Holding Ratio

The transient currents induced by an applied direct voltage (DC) electric field have been measured in the nematic phase of liquid-crystal cells. The experimental results show that the addition of insulating nano-particles such as diamond powders, leads to a decrease in the ion concentration in cells so as to reduce transient currents and threshold voltage drastically. Simultaneously, a high voltage-holding ratio (VHR) is observed in doped cells. Such a high VHR, in comparison with the one in nematic liquid crystals doped by carbon nanotubes, is a superior feature for future liquid crystal display applications.

Optical properties of inorganic AgSb recording thin film

50nm Ag1−xSbx (x=10.8–25.5) thin films were prepared by magnetron sputtering. Thermal analysis shows that the phase change occurs around 250°C. The optical property analysis show that the as-deposited Ag80.9Sb19.1 films have high reflectivity of about 62%–73%. After heat treatment at 300°C, the contrast of Ag80.9Sb19.1 film is 12.5%–17% for wavelengths between 400 and 800nm. Dynamic test shows that using the Ag80.9Sb19.1 film as the memory layer of write once optical disk, a carrier-to-noise ratio of about 45dB can be achieved at λ=657nm, numerical aperture of 0.65, and a linear velocity of 3.5m∕s.

Using Replica Molding Method to Fabricate Alignment-Layer Free Flexible Liquid Crystal Devices

Many kinds of processes have been used to make flexible LCDs. In this paper, we fabricate a flexible LC device by replica molding method – using Poly(dimethylsiloxane) (PDMS) rather than plastic to be the substrate. The PDMS can not only act as the substrate but also the alignment-layer in flexible LCDs; thus there is no need to coat additional alignment-layer on the flexible substrates. One significant achievement of our method is to increase the flexibility of rollable LC devices. The other one is to decrease the processing steps compared with those in other conventional processes.

Flexible Liquid Crystal Cells without Alignment Film

By generating microgroove pattern on the plastic substrate, liquid crystals (LCs) are aligned on the flexible substrates immediately without coating alignment polymer. This flexible LC cell proposed in this paper preserves comparable electro-optical properties while bending. The plastic film and the alignment layer integrated into an alignment substrate could prevent cracks of the additional polymer alignment layer during the bending condition. This method holds promises to be applicable to the roll-to-roll process to increase efficiency of the production.