FTIR Study of Copper Agglomeration during Atomic Layer Deposition of Copper

The growth of of metallic copper by atomic layer deposition (ALD) using copper(I) di-sec-butylacetamidinate $([Cu(^sBu-amd)]_2)$ and molecular hydrogen $(H_2)$ on $SiO_2/Si$ surfaces has been studied. The mechanisms for the initial surface reaction and chemical bonding evolutions with each ALD cycle are inferred from in situ Fourier transform infrared spectroscopy (FTIR) data. Spectroscopic evidence for Cu agglomeration on $SiO_2$ is presented involving the intensity variations of the $SiO_2$ LO/TO phonon modes after chemical reaction with the Cu precursor and after the $H_2$ precursor cycle. These intensity variations are observed over the first 20 ALD cycles at 185°C.Chemistry and Chemical Biolog

In-situ Infrared Characterization During Atomic Layer Deposition of Lanthanum Oxide

Mechanisms of atomic layer deposition (ALD) growth of lanthanum oxide on H-terminated Si(111) using lanthanum tris(N,N′-diisopropylacetamidinate) (La(iPr-MeAMD)3) are investigated using infrared (IR) absorption spectroscopy. The reactivity of this amidinate precursor is high, with almost all surface Si−H bonds consumed after 5 ALD cycles at 300 °C. Gas phase IR spectra show that, although most of the precursor (La(iPr-MeAMD)3) remains intact, a strong feature at 1665 cm−1, characteristic of a hydrogenated and dissociated free ligand with localized electrons in the N−CN bonds, is present. Such partial precursor dissociation in the gas phase is due to hydrolysis by traces of water vapor remaining in the reactor, even after purging. As a result, some Si−O−La bonds are formed upon reaction with the surface during the first La(iPr-MeAMD)3 pulse, prior to any water pulse. During film growth, acetate/carbonate and hydroxyl impurities are incorporated into the film. Annealing to 500 °C in dry N2 removes these impurities but fosters the growth of interfacial SiO2. Deposition at 300 °C leads to decomposition of adsorbed ligands, as evidenced by the formation of cyanamide or carbodiimide vibrational bands (or both) at 1990 and 2110 cm−1, respectively. Despite this decomposition, ideal self-limited ALD growth is maintained because the decomposed ligands are removed by the subsequent water pulse. Growth of pure lanthanum oxide films is often characterized by nonuniform film thickness if purging is not complete because of reversible absorption of water by the La2O3 film. Uniform ALD growth can be maintained without a rigorous dry purge by introducing alternating trimethylaluminum (TMA)/D2O ALD cycles between La/D2O cycles.Chemistry and Chemical Biolog

Quantitative time-averaged gas and liquid distributions using x-ray fluorescence and radiography in atomizing sprays

A method for quantitative measurements of gas and liquid distributions is demonstrated using simultaneous x-ray fluorescence and radiography of both phases in an atomizing coaxial spray. Synchrotron radiation at 10.1 keV from the Advanced Photon Source at Argonne National Laboratory is used for x-ray fluorescence of argon gas and two tracer elements seeded into the liquid stream. Simultaneous time-resolved x-ray radiography combined with timeaveraged dual-tracer fluorescence measurements enabled corrections for reabsorption of x-ray fluorescence photons for accurate, line-of-sight averaged measurements of the distribution of the gas and liquid phases originating from the atomizing nozzle

Autism symptoms in anorexia nervosa: a comparative study with females with autism spectrum disorder

Background: Recent research suggests a link between autism spectrum disorder (ASD) and anorexia nervosa (AN). Individuals with AN show high scores on measures of ASD symptoms, relative to individuals without AN, however, there are currently no studies directly comparing women with AN to women with ASD. The aim of the current study was to examine profiles of ASD symptoms in young women in the acute and recovered stages of AN, women with ASD, and typically developing controls (TD), on both self-report and clinical interview measures. Methods: Four groups of participants aged 12–30 years were included (n = 218): AN, recovered AN (REC), ASD, and TD. Group differences on the Social Responsiveness Scale, 2nd edition (SRS-2), 10-item Autism Quotient (AQ-10), and the Autism Diagnostic Observation Schedule, 2nd edition (ADOS-2) were examined. To explore similarities and differences in specific symptom profiles associated with AN and ASD, individual item endorsement on the ADOS-2 was also examined in AN, REC, and ASD. Results: Across measures, women with ASD showed the highest scores, and TDs the lowest. Generally, individuals with AN and REC showed intermediate levels of ASD symptoms, scoring between the other two groups. However, AN and ASD did not differ on restricted interests and repetitive behaviour subscales. The ADOS-2 item ‘quality of social response’ adequately discriminated between ASD and non-ASD participants. Limitations: A full diagnostic assessment for ASD was not provided for participants with AN/REC, nor were eating disorders assessed in the ASD group. Therefore, some diagnostic overlap between groups is possible. The cross-sectional design is another limitation. Conclusions: The results suggest similarities in scores on both self-report and clinical interview measures in AN and ASD. However, individual ADOS-2 item analyses also revealed subtle differences, particularly in reciprocal social interaction. ASD symptoms may be a combination of both state and trait features in AN