Hopping conduction in heavily doped bulk n-type SiC

The electronic properties of heavily doped n-type 4H, 6H, and 15R SiC have been studied with temperature dependent Hall effect, resistivity measurements, and thermal admittance spectroscopy experiments. Hopping conduction was observed in the resistivity experiments for samples with electron concentrations of 10¹⁷ cm⁻³ or higher. Both band and hopping conduction were observed in all three polytypes in resistivity and Hall effect experiments. The hopping conduction activation energy ε₃ obtained from the resistivity measurements varied from 0.003 to 0.013 eV. The ε₃ value obtained from thermal admittance spectroscopy measurements were slightly lower. The nitrogen ionization levels were observed by thermal admittance spectroscopy only in those samples where hopping conduction was not detected by this experiment. Free carrier activation energy E_a for nitrogen was difficult to determine from temperature dependent Hall effect measurements because of the effects of hopping conduction. A new feature in the apparent carrier concentration vs inverse temperature data in the hopping regime was observed.     

On twisted coalitions and perverse–narcissistic configurations: From positivistic Oedipal third to an existential relational third: A case study.

The authors discuss 4 verbatim sessions of a treatment of a difficult-to-reach patient who can be said in classical nosology to manifest a perverse narcissistic character configuration. The authors discuss the clinical material seen through 2 different lenses based on the classical and relational paradigms. The therapist, Michael Shoshani, worked in a rather classical psychoanalytic model in which perversion was understood in a 1-person or 1-mind mode. With this lens, perversion is seen as a result of the distorted primal scene in which the child is narcissistically inflated, creating the psychotic-like symbolic equation that the child is the father. The father is annihilated and the unique perverse world is created. In contrast, within the relational perspective, the authors see the intersubjective dynamic of mutually knowing and not knowing as being a paramount theme in the treatment of Mr. A. The known and unknown character that a child possesses of his mother's sexuality creates a potential for a relational third. The perversion is the experience of child and parent mutually feeling a sense of being too full of mutual knowledge and not knowing each other at all, leaving a sense of suffocation and stifled vitality. The relational perspective strives to create a transformation from suffocation and stifled vitality to move to a third place offering potential, thus enabling the enigmatic, seductive encounter of the knowing and not knowing to create a sense of mystery, lying between fact and fiction and between sameness and difference, seducing one to want and be, to love while respecting the given universal boundaries. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Polymer thin film photodegradation and photochemical crosslinking: FT-IR imaging, evanescent waveguide spectroscopy, and QCM investigations

Photodegradation and photocrosslinking of benzophenone blended polystyrene (PS) thin films were investigated primarily using Fourier transform infrared (FT-IR) imaging, evanescent waveguide spectroscopy (WS), and quartz crystal microbalance (QCM) methods. The main objective is to observe the changes (spectral and chemical) indicative of these competitive processes in an ultrathin polymer film. This also serves as a model study in the application of combined spectroscopic, optical, and acoustic methods towards understanding crosslinking and degradation phenomena within the same time frame of observation. To induce photocrosslinking, 1,12-dodecanediylbis(oxy-4,1-phenylene)] [bis[phenylmethanone] (2BP12), a small molecule with two benzophenone groups, was blended with PS in solution, spincast onto glass and silicon substrates, and irradiated with ultraviolet light. Photodegradation and benzophenone-mediated crosslinking were observed both directly via functional group spectroscopies and indirectly via their effects on thin film surface properties and morphologies. Atomic force microscopy (AFM) and QCM were used to elucidate local morphology change and mass-uptake kinetics in the presence of O₂ in air, respectively. All results correlated well with the two photoprocesses occurring simultaneously and competitively on these films with the refractive index, thickness, and mass change differing with the presence of 2BP12. Crosslinking was observed to cause an increase in thickness while photodegradation gave a decrease. Both processes resulted in an increase in the refractive index and mass. While various methods have separately identified these observations, this is the first instance that the in situ chemical, optical, and structural dimensionality of the photodegradation and photocrosslinking phenomena in a thin polymer film is correlated within the same time frame of observation.     

Designing Phase Selectively Soluble Polymer-Supports for Dimethylaminopyridine and Phosphine-Ligated Pd(0) Catalysts

Soluble poly(4-alkylstyrene) containing 4-methyl-, 4-tert-butyl, 4-dodecyl-, and 4-octadecylstyrene were formed either with monomers containing dyes-, ligands, or catalysts or with 5–10 mol% of 4-chloromethylstyrene and studied as supports for ligands or catalysts. Studies with dye-labeled polymers showed that polymers containing longer alkyl groups alone or at ca. 10 mol% loading are highly soluble in heptane can be used to separate and recycle organo- and transition metal catalysts.

     

Trajectories emerging from discrete versus continuous processing models in phonological competitor tasks: A commentary on Spivey, Grosjean, and Knoblich (2005).

M. J. Spivey, M. Grosjean, and G. Knoblich (see record 2005-11966-005) showed that in a phonological competitor task, participants' mouse cursor movements showed more curvature toward the competitor item when the competitor and target were phonologically similar than when the competitor and target were phonologically dissimilar. Spivey et al. interpreted this result as evidence for continuous cascading of information during the processing of spoken words. Here we show that the results of Spivey et al.need not be ascribed to continuous speech processing. Instead, their results can be ascribed to discrete processing of speech, provided one appeals to an already supported model of motor control that asserts that switching movements from 1 target to another relies on superposition of the 2nd movement onto the 1st. The latter process is a continuous cascade, a fact that indirectly strengthens the plausibility of continuous cascade models. However, the fact that we can simulate the results of Spivey et al.with a continuous motor output model and a discrete perceptual model shows that the implications of Spivey et al.'s experiment are less clear than these authors supposed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Deep levels in undoped Si1−xGex grown by gas-source molecular beam epitaxy

Deep levels have been identified and characterized in undoped Si_1−xGe_x alloys grown on silicon substrates by gas-source molecular beam epitaxy. Hole traps in the p-type layers have activation energies ranging from 0.029–0.45 eV and capture cross sections (σ_∞ ranging from 10⁻⁹ to 10⁻²⁰ cm². Possible origins of these centers are discussed.     

Effects of substrate surface preparation on chemical vapor deposition growth of 4H-SiC epitaxial layers

The effects of chemical mechanical polish (CMP) and pre-growth oxidation and etching of vicinal 4H−SiC substrates on the quality of epitaxial films have been investigated. Samples with and without a collodial silica CMP and oxidation/etch treatment were studied with optical microscopy, cross section transmission electron microscopy (TEM) and atomic force microscopy (AFM) before and after chemical vapor deposition. Evidence of polishing damage was evident prior to growth in all samples without CMP treatment. Oxidation and etching appeared to generate defects by preferential etching of bulk defects such as dislocations and low angle grain boundaries. Evidence of the polishing damage remained after chemical vapor deposition (CVD) growth on the samples without CMP and the defect density was worse for the oxidized samples compared to the unoxidized ones. The unoxidized CMP wafer had the lowest defect density and rms roughness of the samples studied.     

缅甸蒙育瓦铜矿床——晚中新世浅成热液体系中的一种斑岩全国矿床

蒙育瓦铜矿区由4个矿床组成,为东南亚第二大铜矿.文章在分析总结该矿区区域构造、矿化围岩、地层年代、成矿模式的基础上,认为该区矿化作用是由岩浆源SO2气体从安山斑岩岩脉底部的结晶熔体中上升,与下渗的大气水相互反应凝结形成.这种岩浆与上升的变质水以及向东俯冲过程中的印度洋壳板块在缅甸板块下方的部分熔融有关.推断出在蒙育瓦矿床的下部可能存在一个隐伏斑岩铜矿.