Breaking Through the Noise: Literacy Teachers in the Face of Accountability, Evaluation, and Reform

In an era of increased accountability, it is important to understand how exemplary teachers navigate the demands placed on them by their schools, districts, and states in order to support student learning aligned with their beliefs of effective instruction. To understand these negotiations, tensions facing exemplary literacy teachers were examined through a qualitative interview study. Participants included nineteen experienced PK-6th grade teachers from across the U.S. Results of the study indicate that teachers experience discrepancies between their beliefs and state and local mandates, and they discuss a variety of strategies for negotiating these discrepancies. Findings suggest that schools can support effective literacy instruction by cultivating cultures of autonomy for teachers and strengthening teachers’ sense of agency

Reaction mechanisms of atomic layer deposition of TaNx from Ta(NMe2)5 precursor and H2-based plasmas

The reaction mechanisms of plasma-assisted atomic layer deposition (ALD) of TaNx using Ta(NMe2)5 were studied using quadrupole mass spectrometry (QMS). The fact that molecule dissociation and formation in the plasma have to be considered for such ALD processes was illustrated by the observation of 4% NH3 in a H2-N2 (1:1) plasma. Using QMS measurements the reaction products during growth of conductive TaNx using a H2 plasma were determined. During the Ta(NMe2)5 exposure the reaction product HNMe2 was detected. The amount of adsorbed Ta(NMe2)5 and the amount of HNMe2 released were found to depend on the number of surface groups generated during the plasma step. At the beginning of the plasma exposure step the molecules HNMe2, CH4, HCN, and C2H2 were measured. After an extended period of plasma exposure, the reaction products CH4 and C2H2 were still present in the plasma. This change in the composition of the reaction products can be explained by an interplay of aspects including the plasma-surface interaction, the ALD surface reactions, and the reactions of products within the plasma. The species formed in the plasma (e.g., CHx radicals) can re-deposit on the surface and influence to a large extent the TaNx material composition and propertie

Low-temperature deposition of TiN by plasma-assisted atomic layer deposition

Titanium nitride (TiN) films were deposited by a plasma-assisted at. layer deposition (PA-ALD) process, based on TiCl4 precursor dosing and remote H2-N2 plasma exposure, at temps. ranging from 100 to 400 DegC. The plasma, the PA-ALD process, and the resulting TiN material properties were extensively investigated. The plasma was studied by optical emission spectroscopy and Langmuir probe, revealing an ion d. of 109 cm-3 and an electron temp. of 3.5 eV just above the substrate. Under floating conditions there is thus a considerable ion flux towards the substrate per ALD cycle with a typical ion energy of .apprx.15 eV. TiN film growth was studied by in situ spectroscopic ellipsometry, revealing self-limiting surface reactions for the complete temp. range. At 100 DegC the growth rate of 0.3 A/cycle was found to be significantly lower than the growth rate of 0.6 A/cycle at 400 DegC. The stoichiometry of the films varied with the plasma exposure time, while the Cl content was mostly affected by the deposition temp. (2.1 atom % at 100 DegC to 0.07 atom % at 400 DegC). Resistivities as low as 71 mW cm were obtained at a temp. of 400 DegC, while at 100 DegC a fair resistivity of 209 mW cm was reached. These results show that PA-ALD with TiCl4 and H2-N2 plasma is well suited for low-temp. deposition of high-quality TiN films. [on SciFinder (R)

Application of atmospheric pressure glow discharge (APGD) for deposition of thin silica like films on polymeric webs

Silica-like films were deposited on PEN and PET polymeric foils in atmospheric pressure glow discharge (APGD) in a roll-to-roll reactor open to ambient air. APGD was ignited in a mixture of inexpensive carrying gas argon and nitrogen with oxygen and hexamethyldisiloxane (HMDSO) precursor. The uniform diffuse glow in various gas mixtures was sustained by utilizing electronic stabilization network. APGD operation in air for a present setup was demonstrated. The contribution of different deposition mechanisms to the resulting silica-like film is discussed. The dependence of film structure and chemical composition on the conditions during deposition process was studied by means of SEM, ATR-FTIR and XPS analysis. The influence of oxidant concentration on the deposited film properties is analyzed and discussed

Optical emission spectroscopy on Ar/N/sub 2/ and Ar/N/sub 2//C/sub 2/H/sub 2/ expanding thermal plasmas

This work has been carried out in connection with the possibilities to deposit carbon nitride materials by expansion thermal plasma assisted chemical vapour deposition (ETP-A-CVD). With the same technique high deposition rates and good quality a-Si:H and a-C:H materials have been obtained. A study of the intensity of atomic lines and molecular bands in a Ar/N/sub 2/ and Ar/N/sub 2//C/sub 2/H/sub 2/ expanding thermal plasma has been performed. In the case of the Ar/N/sub 2//C/sub 2/H/sub 2/ mixture rotational and vibrational temperatures were obtained by comparing computer simulated spectra of the CN(B/sup 2/ Sigma -X/sup 2/ Sigma , Delta v=0) spectral system bands with the experimental spectra. The CN ground state density is determined by taking into account the self-absorption of the CN band

New ultrahigh vacuum setup and advanced diagnostic techniques for studying a-Si:H film growth by radical beams

A new ultrahigh vacuum setup is presented which is designed for studying the surface science aspects of a-Si:H film growth using various advanced optical diagnostic techniques. The setup is equipped with plasma and radical sources which produce well-defined radicals beams such that the a-Si:H deposition process can be mimicked. In this paper the initial experiments with respect to deposition of a-Si:H using a hot wire source and etching of a-Si:H by atomic hydrogen are presented. These processes are monitored by real time spectroscopic ellipsometry and the etch yield of Si by atomic hydrogen is quantified to be 0.005±0.002 Si atoms per incoming H atom

Application of atmospheric pressure glow discharge (APGD) for deposition of thin silica like films on polymeric webs

Silica-like films were deposited on PEN and PET polymeric foils in atmospheric pressure glow discharge (APGD) in a roll-to-roll reactor open to ambient air. APGD was ignited in a mixture of inexpensive carrying gas argon and nitrogen with oxygen and hexamethyldisiloxane (HMDSO) precursor. The uniform diffuse glow in various gas mixtures was sustained by utilizing electronic stabilization network. APGD operation in air for a present setup was demonstrated. The contribution of different deposition mechanisms to the resulting silica-like film is discussed. The dependence of film structure and chemical composition on the conditions during deposition process was studied by means of SEM, ATR-FTIR and XPS analysis. The influence of oxidant concentration on the deposited film properties is analyzed and discussed

In situ spectroscopic ellipsometry for atomic layer deposition

The application of in situ spectroscopic ellipsometry during thin film synthesis by atomic layer deposition (ALD) is examined for results obtained on Al2O3, TaN2, and TiN films with thicknesses ranging from 0.1 to 100 nm. By analyzing the film thickness and the energy dispersion of the optical constants of the films, the layer-by-layer growth and material properties of the ALD films can be studied in detail. The growth rate per cycle and the nucleation behavior of the films can be addressed by monitoring the thickness as a function of the number of cycles. It is shown that from the energy dispersion relation, insight into the conductive properties of metallic films can be derived. Moreover, the shape of the dispersion relation can be used to discriminate between different material compositions