Selection Of Dielectric Material Research Articles

Characterization of cylindrical terahertz metallic hollow waveguide with multiple dielectric layers

Dielectric-coated metallic hollow waveguides (DMHW) are drawing considerable attention for their application in terahertz (THz) waveguiding. This paper theoretically analyzes the multilayer structure to reduce the transmission and bending loss of DMHW. The efficiency of THz multilayer DMHW depends on a proper selection of dielectric materials and geometrical parameters. The low-loss properties are demonstrated by studying the multilayer gold waveguides with a stack of polypropylene (PP) and Si-doped polypropylene (PP(Si)). Comparisons are made with single-layer Au/PP and Au-only waveguides. The effect of dielectric absorption is discussed in detail. It is found that low index dielectric causes more additional loss than that of high index dielectric layers. Several design considerations for the THz multilayer DMHW are pointed out by studying the effects of multilayer structure parameters with a stack of polyethylene (PE) and TiO(2)-doped polyethylene (PE(TiO2)). We conclude that the inner radius of the waveguide and the refractive indices of the dielectrics tend to be larger in order to reduce the influence of material absorption. An optimal value exists for the total number of layers when the dielectrics are absorptive. The absorption tolerances are pointed out to guarantee a smaller loss for multilayer DMHW than that of metal-only waveguide. Finally, a fabrication method for THz multilayer DMHW Ag/PE/PE(TiO2) is proposed based on co-rolling technique.

Impact of Dielectric Material Selection on Electrical Characteristics of High-k/Ge Devices

The impact of high-k material selection on the electrical characteristics of high-k/Ge MIS capacitors is investigated. The Y2O3/Ge can maintain good electrical characteristics even after annealing at 600{degree sign}C, while HfO2/Ge seriously degrades. The Ge diffusion into Y2O3 occurs during the annealing, but the characteristics of MIS capacitors do not change even by an intentional doping of Ge into high-k films. The Ge substrate quality is not significantly affected by metal diffusion, neither. These results clearly show that the critical difference between HfO2/Ge and Y2O3/Ge systems is, the ability to form a high quality interface through interface reaction.

Impact of Dielectric Material Selection on Electrical Characteristics of High-k/Ge Devices

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