Graphene as Transparent Electrode for Direct Observation of Hole Photoemission from Silicon to Oxide

The outstanding electrical and optical properties of graphene make it an excellent alternative as a transparent electrode. Here we demonstrate the application of graphene as collector material in internal photoemission (IPE) spectroscopy; enabling the direct observation of both electron and hole injections at a Si/Al2O3 interface and successfully overcoming the long-standing difficulty of detecting holes injected from a semiconductor emitter in IPE measurements. The observed electron and hole barrier heights are 3.5 eV and 4.1 eV, respectively. Thus the bandgap of Al2O3 can be further deduced to be 6.5 eV, in close agreement with the valued obtained by vacuum ultraviolet spectroscopic ellipsometry analysis. The detailed optical modeling of a graphene/Al2O3/Si stack reveals that by using graphene in IPE measurements the carrier injection from the emitter is significantly enhanced and the contribution of carrier injection from the collector electrode is minimal. The method can be readily extended to various IPE test structures for a complete band alignment analysis and interface characterization.Comment: 15 pages, 5 figure

Analyzing capacitance-voltage measurements of vertical wrapped-gated nanowires

The capacitance of arrays of vertical wrapped-gate InAs nanowires are analyzed. With the help of a Poisson-Schr"odinger solver, information about the doping density can be obtained directly. Further features in the measured capacitance-voltage characteristics can be attributed to the presence of surface states as well as the coexistence of electrons and holes in the wire. For both scenarios, quantitative estimates are provided. It is furthermore shown that the difference between the actual capacitance and the geometrical limit is quite large, and depends strongly on the nanowire material.Comment: 15 pages, 6 Figures included, to appear in Nanotechnolog

Effects of Three Conferencing Procedures on the Academic Productivity of LD and NLD Adolescents

This research was published by the KU Center for Research on Learning, formerly known as the University of Kansas Institute for Research in Learning Disabilities.The effects of teacher and parent conferencing procedures on lesson completion by LD and NLD adolescents in a learning center were investigated. Following teacher conferences, students showed initial increases; however, these were not maintained. Following parent conferences, student responses showed great variability. Overall, both procedures encouraged initial increases in lesson completion, but magnitude of change was minimal; neither produced generalization or maintenance effects

Characterization and control of unconfined lateral diffusion under stencil masks

A quantitative study of the spreading behavior of electron-beam-evaporated Al, Au, Cr, Ge, Pt, and Ti on oxidized Si substrates has been performed using translated stencil masks. At least two mechanisms are needed to account for the lateral spreading of the deposited materials: The deposition edge moves by a Fickian diffusion with a diffusion coefficient of 6.7nm2/s6.7nm2∕s at 45°C45°C which is approximately independent of the deposited material. Once under the stencil mask, the deposited material spreads 0.1–2μm0.1–2μm (at 45°C45°C for under 2h2h), in a thin layer as a result of surface diffusion. The evaporation in N2N2 or O2O2 at 50μTorr50μTorr significantly suppresses the spreading with Ti showing the greatest reduction of (7–8)×

Universal analytic model for tunnel FET circuit simulation

A simple analytic model based on the Kane-Sze formula is used to describe the current-voltage characteristics of tunnel field-effect transistors (TFETs). This model captures the unique features of the TFET including the decrease in subthreshold swing with drain current and the superlinear onset of the output characteristic. The model also captures the ambipolar current characteristic at negative gate-source bias and the negative differential resistance for negative drain-source biases. A simple empirical capacitance model is also included to enable circuit simulation. The model has fairly general validity and is not specific to a particular TFET geometry. Good agreement is shown with published atomistic simulations of an InAs double-gate TFET with gate perpendicular to the tunnel junction and with numerical simulations of a broken-gap AlGaSb/InAs TFET with gate in parallel with the tunnel junctio

MRSA Prevalence Between Long-Term Acute Care Hospitals and Acute Care, Critical Access, and Rehabilitation Hospitals in California from 2013-2018

Objectives: A Secondary Data Analysis was conducted to evaluate MRSA prevalence in California Hospitals from 2013-2018 and by county using reported MRSA cases numbers from the California Department of Public Health. Methods: The four data sets for each year were merged and organized by relevant variables: Year, Facility ID, Cases, County, Facility Name, Facility Category, and Hospital Type. After organizing and merging the data, there were inclusion and exclusion criteria to consider: facilities that had zero cases were excluded, the top 6 counties with the highest MRSA cases were included, and the hospital types with highest MRSA cases were included, while the other counties were combined into an ‘Other Hospitals’ category, in the analysis. These decisions were made based on generated frequency tables for each county and hospital type. Results: In 2016, Major Teaching hospitals had the highest number of MRSA cases (66 cases, 26.4%), while in 2015, ‘Other Hospitals’ (4 cases, 2.5%) had the least number of MRSA cases. The majority of cases were predominant with Major Teaching hospitals. Los Angeles had the most MRSA cases overall, with larger Community ( > 250 Beds) Hospitals (32.7%) contributing the most cases, while San Francisco county had the least number of cases in their larger Community ( > 250 Beds) and smaller Community (< 125 Beds) hospitals (0, 0.0%). Conclusion: MRSA cases appear to be more prevalent in Major Teaching hospitals in Los Angeles; possibly peaking in 2016 based on total MRSA cases. However, since MRSA cases was the only measurement available, it is not possible to compare means or test values at the risks of a Type I or Type II error. Therefore, it is not possible to claim whether MRSA cases were significant in hospital in California over time, between counties, or between hospital types. It is possible in the future for this study to be expanded upon using additional variables to evaluate a true difference in MRSA prevalence. This research will benefit epidemiologists and physicians to develop an evidence based system of care to prevent future MRSA cases