Low temperature dopant activation for applications in thin film silicon devices

One of the major areas of research for integrated electronic systems is the development of systems on glass or plastic to optimize the performance/cost tradeoff. These new substrate materials impose stringent constraints on electronic device fabrication, including limitations on chemical and thermal processes. Processes that do not use temperatures greater than 900°C have the increased flexibility for application involving new substrate materials. Silicon is a semiconductor material that can have very different conductive properties based on the levels of impurities. A conventional method of adding impurities is ion implantation. When a substrate is implanted, the ions will break up the ordered crystal lattice and induce damage in the substrate. Interstitial impurities cannot contribute to conductivity; therefore thermal activation is critical for device operation. Annealing is a thermal process that serves two purposes; to re-crystallize the substrate, and to electrically activate the dopant ions. The mechanism of dopant activation in silicon under low-temperature (600°C) annealing conditions is re-crystallization. By exploring rapid thermal annealing (RTA) and furnace processing, a physical model of activation is presented for three dopant ions (boron, phosphorus, and arsenic) over a wide dose range. Sheet resistance and spreading resistance profiling (SRP) have been used to characterize the electrical activation of dopants. Secondary ion mass spectroscopy (SIMS) and x-ray diffraction analysis have been used to determine the distribution of the implanted impuries. Results indicate that eighty to ninety percent of the dopant can be activated at the reduced temperature of 600°C; dependent on the dose implanted

Low Temperature Dopant Activation

A major area of research for integrated electronic systems is the development of systems on glass or plastic to optimize the performance/cost tradeoff. These new substrate materials impose significant constraints on electronic device fabrication, including limitations on chemical and thermal processes. Processes that do not use high temperatures have the increased flexibility needed to be used on new substrate materials. Amorphous silicon thin-film transistors (TFTs) have been fabricated at temperatures below 300°C, where in-situ doped layers are deposited to form the electrode regions. Unfortunately, the electrical activation and carrier mobility in these devices is exceedingly low. The conventional method of adding impurities is ion implantation. Interstitial impurities cannot contribute to conductivity, therefore electrical activation is critical for device operation. ‘When a substrate is implanted with ions, the ions will break up the ordered crystal lattice and induce damage in the substrate. Annealing is a thermal process that serves two purposes, to recrystallize the substrate, and electrically activate dopant ions. While dopant activation at T \u3c 300°C is not possible, anneals done at temperatures below 650°C can be quite effective. The goal of this project is to investigate methods of activating dopants without using the high temperature processes of conventional CMOS. A designed experiment is setup to investigate annealing behavior at low temperatures (T S 650°C). Temperatures centered on 600°C are the focus of this design. Additional factors are investigated including annealing time, ion species, annealing technique (furnace or rapid thermal processing), and the use of pre-amorphization implants

Development of Experimental Icing Simulation Capability for Full-Scale Swept Wings: Hybrid Design Process, Years 1 and 2

This report presents the key results from the first two years of a program to develop experimental icing simulation capabilities for full-scale swept wings. This investigation was undertaken as a part of a larger collaborative research effort on ice accretion and aerodynamics for large-scale swept wings. Ice accretion and the resulting aerodynamic effect on large-scale swept wings presents a significant airplane design and certification challenge to air frame manufacturers, certification authorities, and research organizations alike. While the effect of ice accretion on straight wings has been studied in detail for many years, the available data on swept-wing icing are much more limited, especially for larger scales

The Journal of Microelectronic Research 2005

https://scholarworks.rit.edu/meec_archive/1014/thumbnail.jp

iPSC-Derived Dopamine Neurons Reveal Differences between Monozygotic Twins Discordant for Parkinson’s Disease

SummaryParkinson’s disease (PD) has been attributed to a combination of genetic and nongenetic factors. We studied a set of monozygotic twins harboring the heterozygous glucocerebrosidase mutation (GBA N370S) but clinically discordant for PD. We applied induced pluripotent stem cell (iPSC) technology for PD disease modeling using the twins’ fibroblasts to evaluate and dissect the genetic and nongenetic contributions. Utilizing fluorescence-activated cell sorting, we obtained a homogenous population of “footprint-free” iPSC-derived midbrain dopaminergic (mDA) neurons. The mDA neurons from both twins had ∼50% GBA enzymatic activity, ∼3-fold elevated α-synuclein protein levels, and a reduced capacity to synthesize and release dopamine. Interestingly, the affected twin’s neurons showed an even lower dopamine level, increased monoamine oxidase B (MAO-B) expression, and impaired intrinsic network activity. Overexpression of wild-type GBA and treatment with MAO-B inhibitors normalized α-synuclein and dopamine levels, suggesting a combination therapy for the affected twin

Bordetella pertussis Infection or Vaccination Substantially Protects Mice against B. bronchiseptica Infection

Although B. bronchiseptica efficiently infects a wide range of mammalian hosts and efficiently spreads among them, it is rarely observed in humans. In contrast to the many other hosts of B. bronchiseptica, humans are host to the apparently specialized pathogen B. pertussis, the great majority having immunity due to vaccination, infection or both. Here we explore whether immunity to B. pertussis protects against B. bronchiseptica infection. In a murine model, either infection or vaccination with B. pertussis induced antibodies that recognized antigens of B. bronchiseptica and protected the lower respiratory tract of mice against three phylogenetically disparate strains of B. bronchiseptica that efficiently infect naïve animals. Furthermore, vaccination with purified B. pertussis-derived pertactin, filamentous hemagglutinin or the human acellular vaccine, Adacel, conferred similar protection against B. bronchiseptica challenge. These data indicate that individual immunity to B. pertussis affects B. bronchiseptica infection, and suggest that the high levels of herd immunity against B. pertussis in humans could explain the lack of observed B. bronchiseptica transmission. This could also explain the apparent association of B. bronchiseptica infections with an immunocompromised state

Steroid Hormone Control of Cell Death and Cell Survival: Molecular Insights Using RNAi

The insect steroid hormone ecdysone triggers programmed cell death of obsolete larval tissues during metamorphosis and provides a model system for understanding steroid hormone control of cell death and cell survival. Previous genome-wide expression studies of Drosophila larval salivary glands resulted in the identification of many genes associated with ecdysone-induced cell death and cell survival, but functional verification was lacking. In this study, we test functionally 460 of these genes using RNA interference in ecdysone-treated Drosophila l(2)mbn cells. Cell viability, cell morphology, cell proliferation, and apoptosis assays confirmed the effects of known genes and additionally resulted in the identification of six new pro-death related genes, including sorting nexin-like gene SH3PX1 and Sox box protein Sox14, and 18 new pro-survival genes. Identified genes were further characterized to determine their ecdysone dependency and potential function in cell death regulation. We found that the pro-survival function of five genes (Ras85D, Cp1, CG13784, CG32016, and CG33087), was dependent on ecdysone signaling. The TUNEL assay revealed an additional two genes (Kap-α3 and Smr) with an ecdysone-dependent cell survival function that was associated with reduced cell death. In vitro, Sox14 RNAi reduced the percentage of TUNEL-positive l(2)mbn cells (p<0.05) following ecdysone treatment, and Sox14 overexpression was sufficient to induce apoptosis. In vivo analyses of Sox14-RNAi animals revealed multiple phenotypes characteristic of aberrant or reduced ecdysone signaling, including defects in larval midgut and salivary gland destruction. These studies identify Sox14 as a positive regulator of ecdysone-mediated cell death and provide new insights into the molecular mechanisms underlying the ecdysone signaling network governing cell death and cell survival

Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio