Quark Mass Hierarchy, FCNC and CP violation in a Seesaw model

The seesaw model of quark masses is studied systematically, focusing on its developments. A framework allowing the top quark mass to be of the order of the electroweak symmetry breaking scale, while the remaining light quarks have much smaller masses, due to the seesaw mechanism, is presented. The violation of the GIM mechanism is shown to be small and the tree level FCNC are suppressed naturally. In this model, there are many particles which could contribute to the FCNC in the one-loop level. Parameters of the model are constrained by using the experimental data on K^0-\bar{K}^0 mixing and \epsilon_K. The rare K meson decays K_{L,S} -> \pi^0 \nu \bar{\nu} and K^+ -> \pi^+ \nu \bar{\nu} are also investigated in the model. In these processes the scalar operators (\bar{s}d)(\bar{\nu}_{\tau}\nu_{\tau}), which are derived from box diagrams in the model, play an important role due to an enhancement factor M_K/m_s in the matrix element . It is emphasized that the K_L decay process through the scalar operator is not the CP violating mode, so B(K_L -> \pi^0 \nu \bar{\nu}) remains non-zero even in the CP conserved limit. The pion energy spectra for these processes are predicted.Comment: 42 pages, 13 figures, psfig.sty is require

High-Performance Stacked TiO2-ZrO2 and Si-doped ZrO2 Metal-Insulator-Metal Capacitors

Metal-insulator-metal (MIM) capacitors for DRAM applications have been realised using stacked TiO2-ZrO2 (TiO2/ZrO2 and ZrO2/TiO2) and Si-doped ZrO2 (TiO2/Si-doped ZrO2) dielectrics. High capacitance densities (> 42 fF/mu m(2)), low leakage current densities (< 5 x 10(-7) A/cm(2) at -1 V), and sub-nm EOT (< 0.8 nm) have been achieved. The effects of constant voltage stress on the device characteristics is studied. The structural analysis of the samples is performed by X-ray diffraction measurements, and this is correlated to the electrical characteristics of the devices. The surface chemical states of the films are analyzed through X-ray photoelectron spectroscopy measurements. The doped-dielectric stack (TiO2/Si-doped ZrO2) helps to reduce leakage current density and improve reliability, with a marginal reduction in capacitance density; compared to their undoped counterparts (TiO2/ZrO2 and ZrO2/TiO2). We compare the device performance of the fabricated capacitors with other stacked high-k MIM capacitors reported in recent literature

Performance and Reliability of TiO2/ZrO2/TiO2 (TZT) and AlO-Doped TZT MIM Capacitors

Metal-insulator-metal capacitors for dynamic random access memory applications have been realized using TiO2/ZrO2/TiO2 (TZT) and AlO-doped TZT TiO2/ZrO2/AlO/ZrO2/TiO2 (TZAZT) and TiO2/ZrO2/AlO/ZrO2/AlO/ZrO2/TiO2 (TZAZAZT)] dielectric stacks. High-capacitance densities of 46.6 fF/mu m(2) (for TZT stacks), 46.2 fF/mu m(2) (for TZAZT stacks), and 46.8 fF/mu m(2) (for TZAZAZT stacks) have been achieved. Low leakage current densities of about 4.9 x 10(-8), 5.5x10(-9), and 9.7x10(-9) A/cm(2) (at -1 V) have been obtained for TZT, TZAZT, and TZAZAZT stacks, respectively. We analyze the leakage current mechanisms at different electric field regimes, and compute the trap levels. The effects of constant voltage stress on the device characteristics were studied, and excellent device reliability was demonstrated. The electrical characteristics of the devices were correlated with the structural analysis through X-ray diffraction measurements and the surface chemical states analysis through X-ray photoelectron spectroscopy measurements. The doped-dielectric stacks (AlO-doped TZT: TZAZT and TZAZAZT) help to reduce leakage current density and improve reliability, without substantial reduction in capacitance density, compared with their undoped counterparts (TZT)