Sub-micron, Metal Gate, High-к Dielectric, Implant-free, Enhancement-mode III-V MOSFETs

The performance of 300nm, 500nm and 1μm metal gate, implant free, enhancement mode III-V MOSFETs are reported. Devices are realised using a 10nm MBE grown Ga2O3/(GaxGd1-x)2O3 high-κ (κ=20) dielectric stack grown upon a δ-doped AlGaAs/InGaAs/AlGaAs/GaAs heterostructure. Enhancement mode operation is maintained across the three reported gate lengths with a reduction in threshold voltage from 0.26 V to 0.08 V as the gate dimension is reduced from 1 μm to 300 nm. An increase in transconductance is also observed with reduced gate dimension. Maximum drain current of 420 μA/μm and extrinsic transconductance of 400 µS/µm are obtained from these devices. Gate leakage current of less than 100pA and subthreshold slope of 90 mV/decade were obtained for all gate lengths. These are believed to be the highest performance submicron enhancement mode III-V MOSFETs reported to date

Enhancement Mode n-MOSFET with High-κ Dielectric on GaAs Substrate

In this paper, we report MOS heterostructures grown by molecular beam epitaxy on III-V substrates, employing a high-κ dielectric stack comprised of gallium oxide and gadolinium gallium oxide. Mobilities exceeding 12,000 and 6,000 cm2/Vs, for sheet carrier concentration ns of about 2.5x1012 cm-2 were measured on MOSFET structures on InP and GaAs substrates, respectively. These structures were designed for enhancement mode operation and include a 10 nm thick strained InGa1-xAs channel layer with In mole fraction x of 0.3 and 0.75 on GaAs and InP substrates, respectively

Entropy, Dynamics and Instantaneous Normal Modes in a Random Energy Model

It is shown that the fraction f of imaginary frequency instantaneous normal modes (INM) may be defined and calculated in a random energy model(REM) of liquids. The configurational entropy S and the averaged hopping rate among the states R are also obtained and related to f, with the results R~f and S=a+b*ln(f). The proportionality between R and f is the basis of existing INM theories of diffusion, so the REM further confirms their validity. A link to S opens new avenues for introducing INM into dynamical theories. Liquid 'states' are usually defined by assigning a configuration to the minimum to which it will drain, but the REM naturally treats saddle-barriers on the same footing as minima, which may be a better mapping of the continuum of configurations to discrete states. Requirements of a detailed REM description of liquids are discussed

APC1638T: a mouse model delineating critical domains of the adenomatous polyposis coli protein involved in tumorigenesis and development

This is the publisher's version, also available electronically from "http://genesdev.cshlp.org".The adenomatous polyposis coli (APC) gene is considered as the true gatekeeper of colonic epithelial proliferation: It is mutated in the majority of colorectal tumors, and mutations occur at early stages of tumor development in mouse and man. These mutant proteins lack most of the seven 20-amino-acid repeats and all SAMP motifs that have been associated with down-regulation of intracellular β-catenin levels. In addition, they lack the carboxy-terminal domains that bind to DLG, EB1, and microtubulin. APC also appears to be essential in development because homozygosity for mouse Apcmutations invariably results in early embryonic lethality. Here, we describe the generation of a mouse model carrying a targeted mutation at codon 1638 of the mouse Apc gene, Apc1638T, resulting in a truncated Apc protein encompassing three of the seven 20 amino acid repeats and one SAMP motif, but missing all of the carboxy-terminal domains thought to be associated with tumorigenesis. Surprisingly, homozygosity for the Apc1638T mutation is compatible with postnatal life. However, homozygous mutant animals are characterized by growth retardation, a reduced postnatal viability on the B6 genetic background, the absence of preputial glands, and the formation of nipple-associated cysts. Most importantly,Apc 1638T/1638T animals that survive to adulthood are tumor free. Although the full complement of Apc1638T is sufficient for proper β-catenin signaling, dosage reductions of the truncated protein result in increasingly severe defects in β-catenin regulation. The SAMP motif retained in Apc1638T also appears to be important for this function as shown by analysis of the Apc1572T protein in which its targeted deletion results in a further reduction in the ability of properly controlling β-catenin/Tcf signaling. These results indicate that the association with DLG, EB1, and microtubulin is less critical for the maintenance of homeostasis by APC than has been suggested previously, and that proper β-catenin regulation by APC appears to be required for normal embryonic development and tumor suppression

Quantum transport using the Ford-Kac-Mazur formalism

The Ford-Kac-Mazur formalism is used to study quantum transport in (1) electronic and (2) harmonic oscillator systems connected to general reservoirs. It is shown that for non-interacting systems the method is easy to implement and is used to obtain many exact results on electrical and thermal transport in one-dimensional disordered wires. Some of these have earlier been obtained using nonequilibrium Green function methods. We examine the role that reservoirs and contacts can have on determining the transport properties of a wire and find several interesting effects.Comment: 10 pages, 4 figure

Are diamonds a MEMS\u27 best friend?

Next-generation military and civilian communication systems will require technologies capable of handling data/ audio, and video simultaneously while supporting multiple RF systems operating in several different frequency bands from the MHz to the GHz range [1]. RF microelectromechanical/nanoelectromechanical (MEMS/NEMS) devices, such as resonators and switches, are attractive to industry as they offer a means by which performance can be greatly improved for wireless applications while at the same time potentially reducing overall size and weight as well as manufacturing costs

Mean-atom-trajectory model for the velocity autocorrelation function of monatomic liquids

We present a model for the motion of an average atom in a liquid or supercooled liquid state and apply it to calculations of the velocity autocorrelation function $Z(t)$ and diffusion coefficient $D$. The model trajectory consists of oscillations at a distribution of frequencies characteristic of the normal modes of a single potential valley, interspersed with position- and velocity-conserving transits to similar adjacent valleys. The resulting predictions for $Z(t)$ and $D$ agree remarkably well with MD simulations of Na at up to almost three times its melting temperature. Two independent processes in the model relax velocity autocorrelations: (a) dephasing due to the presence of many frequency components, which operates at all temperatures but which produces no diffusion, and (b) the transit process, which increases with increasing temperature and which produces diffusion. Because the model provides a single-atom trajectory in real space and time, including transits, it may be used to calculate all single-atom correlation functions.Comment: LaTeX, 8 figs. This is an updated version of cond-mat/0002057 and cond-mat/0002058 combined Minor changes made to coincide with published versio

Multiple Dimensions of the Moral Majority Platform: Shifting Interest Group Coalitions

The issues raised by the New Political Right and the Moral Majority have overlapped in recent political history. Researchers have assumed that a single additive scale across conservative issues can identify the base of support for the Moral Majority as an organization. We examine general support for the Moral Majority separately from support for six specific issues: teaching creationism, voluntary public school prayer, military defense spending, gun control, pornography and abortion. Data are from a 1982 random sample of adult respondents from Nebraska (N = 1907). Overall, support for the Moral Majority organization is low. Discriminant analysis identifies fundamentalist and evangelical religious affiliation and Biblical literalism as independent predictors of support for the Moral Majority per se. Education increases knowledge of the organization, but does not influence support for it. Respondents with high income levels are more likely to support the Moral Majority organization. These findings contradict theories of both status politics and cultural fundamentalism. Support for the six specific platform items also varies considerably and is affected by religious conservatism and, independently, by other attitudinal and demographic indicators including age, sex, income, rural residence, education and perception of declining economic conditions. These patterns do not entirely fit the predictions of status politics or cultural fundamentalism theories. Rather, they provide evidence that distinct coalitions form on specific issues. Our conclusion is that a simple additive index of support for the Moral Majority masks these differences and oversimplifies complex patterns of coalitions in the religio-political arena

Relationship between birth weight and retinal microvasculature in newborn infants

Objective: The purposes of this study were to determine the normal retinal microvasculature measurements in human infants who are born at term and to determine whether birth weight influences measurements of retinal microvasculature. Study Design: Retinal arteriole and venule measurements were obtained in a cohort of 24 infants who were born at term. Digital images of both the retinas were obtained using a digital retinal camera after pupillary dilation. Result: In all, 24 newborn infants born at term (12 females and 12 males) were analyzed in this study. The measured retinal arteriole diameters were from 66.8 to 147.8 μm (mean, 94.2±19.6 μm), and the venule diameters were from 102.0 to 167.8 μm (mean, 135.2±19.1 μm). Seven babies in the sample had low birth weight (LBW), while 17 babies were born with normal weight. Babies with lower birth weights had larger arteriole (113.1±17.9 μm vs 86.4±14.4 μm; P=0.0009) and venule diameters (151.7±14.9 μm vs 128.4±16.9 μm; P=0.0040). Conclusion: Retinal venules and arterioles in LBW babies are larger compared with those of normal-birth-weight babies. We postulate that the difference observed in our study was due to in utero pathophysiological changes that occurred in the cerebral circulation of growth-restricted fetuses