InSb/CdTe Heterostructures Grown by Molecular Beam Epitaxy

Given the potential for quantum effect device application, the growth, by molecular beam epitaxy, and characterization of InSb-CdTe heterostructures is described. Two procedures for growth of these heterostructures are employed. For the growth of InSb/CdTe double heterostructures, InSb and CdTe layers are grown in separate MBE growth chambers connected via an ultrahigh vacuum transfer module. Here, antimony originating from a compound InSb source oven is used for growth of InSb layers. For the growth of CdTe/InSb multiple quantum well structures, InSb and CdTe layers are grown in a single MBE growth chamber, where antimony is derived from an antimony cracking furnace. To study the optical nature of heteroepitaxially grown InSb, infrared photoluminescence from InSb based double heterostructures has been examined. Despite the transferral of grown layers between III-V and II-VI chambers, luminescence gathered from thick” InSb active layers has shown the existence of recombination features which are similar to bulk InSb. For multilayer structures, grown in a single chamber with the use of an antimony cracker, emphasis has been placed on structural examination by transmission electron microscopy and x-ray diffraction techniques. Examination of multilayer structures by transmission electron microscopy suggests tha t the cracker may be useful for the growth of InSb at low substrate temperatures and low growth rates. Using the cracker, CdTe/InSb superlattice structures have been grown showing multiple satellite peaks in the x-ray diffraction spectrum

Erratum: ‘‘Evidence for field enhanced electron capture by EL2 centers in semi‐insulating GaAs and the effect on GaAs radiation detectors’’ [J. Appl. Phys. 75, 7910 (1994)]

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69985/2/JAPIAU-77-3-1331-1.pd

Evidence for field enhanced electron capture by EL2 centers in semi‐insulating GaAs and the effect on GaAs radiation detectors

The performance of Schottky contact semiconductor radiation detectors fabricated from semi‐insulating GaAs is highly sensitive to charged impurities and defects in the material. The observed behavior of semi‐insulating GaAs Schottky barrier alpha particle detectors does not match well with models that treat the semi‐insulating material as either perfectly intrinsic or as material with deep donors (EL2) of constant capture cross section compensated with shallow acceptors. We propose an explanation for the discrepancy based on enhanced capture of electrons by EL2 centers at high electric fields and the resulting formation of a quasineutral region in the GaAs. Presented is a simple model including field enhanced electron capture which shows good agreement with experimental alpha particle pulse height measurements.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71231/2/JAPIAU-75-12-7910-1.pd

Evidence for field enhanced electron capture by EL2 centers in semi-insulating GaAs and the effect on GaAs radiation detectors

The performance of Schottky contact semiconductor radiation detectors fabricated from semi-insulating GaAs is highly sensitive to charged impurities and defects in the material. The observed behavior of semi-insulating GaAs Schottky barrier alpha particle detectors does not match well with models that treat the semi-insulating material as either perfectly intrinsic or as material with deep donors (EL2) of constant capture cross section compensated with shallow acceptors. We propose an explanation for the discrepancy based on enhanced capture of electrons by EL2 centers at high electric fields and the resulting formation of a quasineutral region in the GaAs. Presented is a simple model including field enhanced electron capture which shows good agreement with experimental alpha particle pulse height measurements

1970: Abilene Christian College Bible Lectures - Full Text

THE APOSTLES’ DOCTRINE Being the Abilene Christian College Annual Bible Lectures 1970 Published by ABILENE CHRISTIAN COLLEGE BOOK STORE ACC Station Abilene, Texas 7960

1954: Abilene Christian College Bible Lectures - Full Text

Preface The 1954 Abilene Christian College Lectureship was one of the best attended and most successful in the history of the school. Considerable interest was manifested in the timely theme, “Overcoming Dangerous Tendencies,” and in the two special topics, “Ways and Means of Doing Mission Work,” and “Caring For Widows and Orphans.” The reports from the mission fields were highly stimulating, and all in all, the speeches were unusually high caliber. The Panel Discussions were also on timely subjects and well presented. They received a warm response, as did also the thirty classes that were conducted each day. These classes were taught by persons expert in their particular fields, and covered a wide range of interests to the faithful, working Christian. We at Abilene Christian College predict for this book of Lectures a wide and hearty reception, and believe that its reading will issue in profit to the individual and to the church at large. J. D. Thomas Lectureship Directo

Ecosystem Resilience and Threshold Response in the Galápagos Coastal Zone

Background: The Intergovernmental Panel on Climate Change (IPCC) provides a conservative estimate on rates of sea-level rise of 3.8 mm yr⁻¹ at the end of the 21st century, which may have a detrimental effect on ecologically important mangrove ecosystems. Understanding factors influencing the long-term resilience of these communities is critical but poorly understood. We investigate ecological resilience in a coastal mangrove community from the Galápagos Islands over the last 2700 years using three research questions: What are the 'fast and slow' processes operating in the coastal zone? Is there evidence for a threshold response? How can the past inform us about the resilience of the modern system?Methodology/Principal Findings: Palaeoecological methods (AMS radiocarbon dating, stable carbon isotopes (δ13C)) were used to reconstruct sedimentation rates and ecological change over the past 2,700 years at Diablas lagoon, Isabela, Galápagos. Bulk geochemical analysis was also used to determine local environmental changes, and salinity was reconstructed using a diatom transfer function. Changes in relative sea level (RSL) were estimated using a glacio-isostatic adjustment model. Non-linear behaviour was observed in the Diablas mangrove ecosystem as it responded to increased salinities following exposure to tidal inundations. A negative feedback was observed which enabled the mangrove canopy to accrete vertically, but disturbances may have opened up the canopy and contributed to an erosion of resilience over time. A combination of drier climatic conditions and a slight fall in RSL then resulted in a threshold response, from a mangrove community to a microbial mat.Conclusions/Significance: Palaeoecological records can provide important information on the nature of non-linear behaviour by identifying thresholds within ecological systems, and in outlining responses to 'fast and slow' environmental change between alternative stable states. This study highlights the need to incorporate a long-term ecological perspective when designing strategies for maximizing coastal resilience.</p

A Roadmap for HEP Software and Computing R&D for the 2020s

Particle physics has an ambitious and broad experimental programme for the coming decades. This programme requires large investments in detector hardware, either to build new facilities and experiments, or to upgrade existing ones. Similarly, it requires commensurate investment in the R&D of software to acquire, manage, process, and analyse the shear amounts of data to be recorded. In planning for the HL-LHC in particular, it is critical that all of the collaborating stakeholders agree on the software goals and priorities, and that the efforts complement each other. In this spirit, this white paper describes the R&D activities required to prepare for this software upgrade.Peer reviewe