C-V characteristics of metal-titanium dioxide-silicon capacitors

Titanium dioxide capacitors were fabricated on silicon wafers using electron-beam evaporation. The TiO₂ films varied in thickness from 500 to 2000 Å. Post-deposition oxidation at 1000°C in dry O₂ was used to promote stoichiometric conversion of the films to the rutile phase. Capacitive densities of greater than 2 pf/sq. mil were obtained (dielectric constants ranged from 4 to 40). For long oxidation times, significant silicon dioxide grows under the TiO₂ as a result of oxygen diffusing through the TiO₂ film. Titanium was also shown to diffuse into the silicon during the oxidation cycle resulting in an n-type diffusion. Surface state densities ranging from 10¹¹ to 5 × 10¹¹ cm^?2 eV^?1 at midgap were obtained for good devices. Longer oxidation times result in lower capacitance, leakage current and surface state density.     

Dielectric properties and charge storage characteristics of the metal-TiO2-SiO2-Si structure

Semiconductor memory elements have been fabricated on silicon utilizing electron-beam evaporated TiO₂ as the charge storage insulator medium. The dielectric and charge storage properties of TiO₂ films have been characterized as a function of TiO₂ deposition conditions and post-deposition annealing. Our results show that both dielectric constant and charge storage properties are enhanced by evaporation of the TiO₂ in an oxygen ambient and substrate heating during evaporation. Post-deposition annealing in an oxygen ambient is also shown to increase the dielectric constant. M-TiO₂-SiO₂-Si structures with a 1000 Å layer of TiO₂ typically exhibit 5 V memory windows for a ±15 V write/erase pulse.     

Non-volatile memory properties of metal/SrTiO3/SiO2/Si structures

Non-volatile MIOS-type semiconductor memory elements were fabricated on silicon using electron-beam-evaporated SrTiO₃ as the second insulator. The charge storage properties were characterized for Au/SrTiO₃/SiO₂/Si structures. Our results show that a short-time post-deposition oxygen annealing is essential to anneal out the radiation damage resulting from electron beam deposition. The devices on n-type silicon substrates show fast switching for a positive applied pulse and a much lower switching speed (longer than 20 ms) for a negative pulse, which is believed to be caused by the minority carrier restriction. The devices show a logarithmic decay of the flat-band voltage as a function of time, with a rate of 0.4 V decade^-1 for stored electrons and 0.5 V decade^-1 for stored holes. The devices can survive 10⁴ write-erase cycles of endurance testing. An inversion of the surface silicon layer is found for devices on p-type substrates subjected to high temperature oxygen annealing.     

Current-voltage characteristics of metal-titanium dioxide-silicon structures

Metal-titanium dioxide-silicon capacitors were fabricated using electron- beam-evaporated titanium dioxide as the insulating layer. The effects of the titanium dioxide deposition conditions and post-deposition oxidation on the current-voltage characteristics were investigated. A time-dependent current was observed and modeled. Diffusion of the titanium from the titanium dioxide layer into the p-type silicon substrates during oxidation of the titanium dioxide film resulted in an n-type diffused layer. Leakage current densities as low as 10^-9 A in^-2 at 10 V applied bias were obtained for a 1000 Å film of titanium dioxide.     

Stability and level of self-esteem as predictors of anger arousal and hostility.

We examined stability of self-esteem and level of self-esteem as predictors of dispositional tendencies to experience anger and hostility. We reasoned that individuals with unstable high self-esteem would report especially high tendencies to experience anger and hostility, and that individuals with stable high self-esteem would report particularly low tendencies. We expected individuals with stable and unstable low self-esteem to fall between these two extremes. These predictions were derived from an analysis of anger and hostility that emphasized the instigating role of threats to self-esteem. Stability of self-esteem was assessed through multiple assessments of global self-esteem in naturalistic settings. Results revealed the predicted pattern for the tendency to experience anger and a "motor" component of hostility. The importance of considering both stability and level of self-esteem in analyses of anger and hostility is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electromagnetic scattering from a dielectric-coated sphere with anembedded impedance film

The electromagnetic scattering from a multilayered sphere modal solution of Wait (1963) is modified to allow the inclusion of infinitesimally thin impedance films at layer boundaries. The modified solution is implemented in a computer algorithm and the scattering from an aluminum sphere coated with a dielectric Delrin^TM layer containing an embedded impedance film is computed. This target was fabricated and laboratory measurements performed in the 2-18 GHz region are in good agreement with computations     

Electrical characteristics of GaAsP Schottky barrier diodes

Schottky barrier diodes of chromium on n-type epitaxial gallium arsenide phosphide (GaAsP) were studied from 25°C to 440°C. The diodes showed significant rectification properties up to a temperature of 440°C. At high temperature the reverse leakage current was 1.15 mA at 25 V with a diode area of 1.14×10⁻³ cm² as compared with 0.25-μA current at room temperature. The n factor derived from the slope of the ln I vs. V curves was 1.1. The barrier height for chromium was found to be 1.25 eV from the capacitance measurements and 1.12 eV from the saturation current vs. temperature measurements. The slope of the C-V curves yielded a carrier concentration of 6.0×10¹⁵ carriers per cm³.     

A representation theorem based analysis of two-dimensionalelectromagnetic scattering from materials and resistive cards

Representation-theorem-based surface integral operators are presented and used to predict electromagnetic scattering from a material body with an embedded resistive card. The integral operators are obtained from a representation theorem for the 2-D Helmholtz equation in a region with constant electrical properties characterized by complex permittivity and permeability. A resistive card embedded in the region is introduced by enforcing a resistive boundary condition on the representation theorem integrals as the thickness of a geometrically thin region surrounding an embedded card approaches zero. Surface integral operators are obtained by letting the field point in the representation theorem equations approach material boundaries and resistive cards. Multiple regions with constant electrical properties (including perfect conductors) are allowed by enforcing boundary conditions between regions. Two polarizations of normally incident plane wave radiation are considered. Prediction and experiment are in good agreement for a resistive card embedded in a bulk material