Scaling analysis of electron transport through metal-semiconducting carbon nanotube interfaces: Evolution from the molecular limit to the bulk limit

We present a scaling analysis of electronic and transport properties of metal-semiconducting carbon nanotube interfaces as a function of the nanotube length within the coherent transport regime, which takes fully into account atomic-scale electronic structure and three-dimensional electrostatics of the metal-nanotube interface using a real-space Green's function based self-consistent tight-binding theory. As the first example, we examine devices formed by attaching finite-size single-wall carbon nanotubes (SWNT) to both high- and low- work function metallic electrodes through the dangling bonds at the end. We analyze the nature of Schottky barrier formation at the metal-nanotube interface by examining the electrostatics, the band lineup and the conductance of the metal-SWNT molecule-metal junction as a function of the SWNT molecule length and metal-SWNT coupling strength. We show that the confined cylindrical geometry and the atomistic nature of electronic processes across the metal-SWNT interface leads to a different physical picture of band alignment from that of the planar metal-semiconductor interface. We analyze the temperature and length dependence of the conductance of the SWNT junctions, which shows a transition from tunneling- to thermal activation-dominated transport with increasing nanotube length. The temperature dependence of the conductance is much weaker than that of the planar metal-semiconductor interface due to the finite number of conduction channels within the SWNT junctions. We find that the current-voltage characteristics of the metal-SWNT molecule-metal junctions are sensitive to models of the potential response to the applied source/drain bias voltages.Comment: Minor revision to appear in Phys. Rev. B. Color figures available in the online PRB version or upon request to: [email protected]

NACA Research Memorandums

Report presenting the effects of inclining the plane of the inlet on the performance of several converging-diverging diffusers at zero angle of attack for a range of Mach numbers. Results regarding Schileren photographs, static-pressure recovery, total-pressure loss, and total-pressure distributions are provided

Inventory of Complicated Spiritual Grief: Development and initial validation of a new measure

Although spirituality often has been associated with better outcomes following bereavement, it can be significantly challenged by loss as well. Studies have shown that some bereaved individuals suffer profoundly not only in relation to the death of their loved one but also in their relationship with God and their faith community, a condition known as complicated spiritual grief (CSG). However, to date, in the absence of a simple, multidimensional, and well-validated measure of spiritual crisis following loss, investigators have measured CSG with nongrief-specific instruments. In this study, the authors tested the reliability and validity of a newly developed measure of CSG, called the Inventory of Complicated Spiritual Grief (ICSG). With 2 diverse samples of bereaved adult Christians (total n = 304), the authors found that the ICSG had strong internal consistency, and high test-retest reliability for both subscales in a subsample of participants. Analyses of both samples supported a 2-factor model, with one factor measuring Insecurity with God and the other assessing Disruption in Religious Practice. Analyses further supported the convergent and incremental validity of the 18-item ICSG relative to other theoretically similar instruments and measures of poor bereavement outcome, suggesting its usefulness in clinical research and practice

A Dual Magnetic Tunnel Junction‐Based Neuromorphic Device

With the advent of artificial intelligence (AI) in computational devices technology, various synaptic array architectures are proposed for neuromorphic computing applications. Among them, the non-volatile memory (NVM) architectures are very promising for their small cell size, ultra-low energy consumption, and capability for large parallel data processing through 3D configurations capable of multilevel signal processing. Herein, the viability of such magnetic tunnel junction (MTJ)-based synaptic devices via fabrication and characterization of multi-junction spintronic devices is demonstrated, with the experimental results supported through micromagnetic simulations

Number of traps and trap depth position on statistical distribution of random telegraph noise in scaled NAND flash memory

The dependence of random telegraph noise (RTN) amplitude distribution on the number of traps and trap depth position is investigated using three-dimensional Monte Carlo device simulation including random dopant fluctuation (RDF) in a 30 nm NAND multi level flash memory. The Delta V-th tail distribution becomes broad at fixed double traps, indicating that the number of traps greatly affects the worst RTN characteristics. It is also found that for both fixed single and fixed double traps, the Delta V-th distribution in the lowest cell threshold voltage (V-th) state shows the broadest distribution among all cell V-th states. This is because the drain current flows at the channel surface in the lowest cell V-th state, while at a high cell V-th, it flows at the deeper position owing to the fringing coupling between the control gate (CG) and the channel. In this work, the Delta V-th distribution with the number of traps following the Poisson distribution is also considered to cope with the variations in trap number. As a result, it is found that the number of traps is an important factor for understanding RTN characteristics. In addition, considering trap position in the tunnel oxide thickness direction is also an important factor. (C) 2016 The Japan Society of Applied Physic