Influence of inert gases on the reactive high power pulsed magnetron sputtering process of carbon-nitride thin films

The influence of inert gases (Ne, Ar, Kr) on the sputter process of carbon and carbon-nitride (CNx) thin films was studied using reactive high power pulsed magnetron sputtering (HiPIMS). Thin solid films were synthesized in an industrial deposition chamber from a graphite target. The peak target current during HiPIMS processing was found to decrease with increasing inert gas mass. Time averaged and time resolved ion mass spectroscopy showed that the addition of nitrogen, as reactive gas, resulted in less energetic ion species for processes employing Ne, whereas the opposite was noticed when Ar or Kr were employed as inert gas. Processes in nonreactive ambient showed generally lower total ion fluxes for the three different inert gases. As soon as N2 was introduced into the process, the deposition rates for Ne and Ar-containing processes increased significantly. The reactive Kr-process, in contrast, showed slightly lower deposition rates than the nonreactive. The resulting thin films were characterized regarding their bonding and microstructure by x-ray photoelectron spectroscopy and transmission electron microscopy. Reactively deposited CNx thin films in Ar and Kr ambient exhibited an ordering toward a fullerene-like structure, whereas carbon and CNx films deposited in Ne atmosphere were found to be amorphous. This is attributed to an elevated amount of highly energetic particles observed during ion mass spectrometry and indicated by high peak target currents in Ne-containing processes. These results are discussed with respect to the current understanding of the structural evolution of a-C and CNx thin films. VC 2013 American Vacuum Society. [http://dx.doi.org/10.1116/1.4769725

A Test of Sovereignty: Franchise Tax Board of the State of California v. Gilbert P. Hyatt

In Franchise Tax Board of California v. Hyatt, the Supreme Court considers whether to overrule Nevada v. Hall, a 1979 Supreme Court decision. Hall permitted a State to be haled into the court of another State without its consent. In 2016, an evenly divided Supreme Court affirmed Hall 4-4 when faced with the same question, and following a remand to the Nevada Supreme Court, the Court has granted certiorari on this question once again. This Commentary contends that Hall was wrongly decided and should be overruled. The Constitution’s ratification did not alter the status of common-law State sovereign immunity, leaving intact not only State sovereign immunity in a State’s own court but also a State’s immunity to suits in the courts of another State without consent. However, this case, in which the Petitioner has already appeared in the court of another State, is not the appropriate vehicle for overruling Hall. State sovereign immunity should be restored at the next possible opportunity, when a State properly asks a federal court to enforce its common-law immunity from the courts of a sister State. Sovereigns should enjoy immunity not only in their own courts, but also in the courts of their peers

Double Secret Protection: Bridging Federal and State Law To Protect Privacy Rights for Telemental and Mobile Health Users

Mental health care in the United States is plagued by stigma, cost, and access issues that prevent many people from seeking and continuing treatment for mental health conditions. Emergent technology, however, may offer a solution. Through telemental health, patients can connect with providers remotely—avoiding stigmatizing situations that can arise from traditional healthcare delivery, receiving more affordable care, and reaching providers across geographic boundaries. And with mobile health technology, people can use smart phone applications both to self-monitor their mental health and to communicate with their doctors. But people do not want to take advantage of telemental and mobile health unless their privacy is protected. After evaluating the applicability of current health information privacy law to these new forms of treatment, this Note proposes changes to the federal regime to protect privacy rights for telemental and mobile health users

Origin of the anomalous piezoelectric response in wurtzite Scx_xAl1−x_{1-x}N alloys

The origin of the anomalous, 400% increase of the piezoelectric coefficient in Sc$_x$Al$_{1-x}$N alloys is revealed. Quantum mechanical calculations show that the effect is intrinsic. It comes from a strong change in the response of the internal atomic coordinates to strain and pronounced softening of C$_{33}$ elastic constant. The underlying mechanism is the flattening of the energy landscape due to a competition between the parent wurtzite and the so far experimentally unknown hexagonal phases of the alloy. Our observation provides a route for the design of materials with high piezoelectric response.Comment: 10 pages, 4 figures, accepted for publication in Phys. Rev. Let

CrNx Films Prepared by DC Magnetron Sputtering and High-Power Pulsed Magnetron Sputtering: A Comparative Study

Abstract-CrN x (0 ≤ x ≤ 0.91) films synthesized using highpower pulsed magnetron sputtering, also known as high-power impulse magnetron sputtering (HiPIMS), have been compared with those made by conventional direct-current (dc) magnetron sputtering (DCMS) operated at the same average power. The HiPIMS deposition rate relative to the DCMS rate was found to decrease linearly with increasing emission strength from the Cr ions relative to Cr neutrals, in agreement with the predictions of the target-pathway model. The low deposition rate in HiPIMS is thus a direct consequence of the high ionization level (∼56%) of the target material and effective capturing of Cr ions by the cathode potential. Although the HiPIMS deposition rate did not exceed 40% of the DCMS rate, the drop in the relative deposition rate upon increasing the N 2 -to-Ar flow ratio, f N 2 /Ar , was found to be similar for both sputtering techniques. Films prepared by HiPIMS contained similar amounts of atomic nitrogen as the dc-sputtered samples grown at the same f N 2 /Ar , indicating that the nitride formation at the substrate takes place mostly during the time period of the high-power pulses, and the N 2 uptake between the pulses is negligible. The microstructure evolution in the two types of CrN x films, however, differed clearly from each other. A combination of a high substrate bias and a high flux of doubly charged Cr ions present during the HiPIMS discharge led to a disruption of the grain growth and renucleation, which resulted in column-free films with nanosized grains not observed in the conventional DCMS-based process. The comparison of nanoindentation hardness as a function of f N 2 /Ar revealed superior properties of HiPIMS-sputtered films in the entire range of gas compositions. Index Terms-CrN, high-power impulse magnetron sputtering (HiPIMS), high-power pulsed magnetron sputtering, magnetron sputtering

Bonding Structures of ZrHx Thin Films by X-ray Spectroscopy

The variation in local atomic structure and chemical bonding of ZrHx (x=0.15, 0.30, 1.16) magnetron sputtered thin films are investigated by Zr K-edge (1s) X-ray absorption near-edge structure and extended X-ray absorption fine structure spectroscopies. A chemical shift of the Zr K-edge towards higher energy with increasing hydrogen content is observed due to charge-transfer and an ionic or polar covalent bonding component between the Zr 4d and the H 1s states with increasing valency for Zr. We find an increase in the Zr-Zr bond distance with increasing hydrogen content from 3.160 {\AA} in the hexagonal closest-packed metal (alpha-phase) to 3.395 {\AA} in the understoichiometric delta-ZrHx film (CaF2-type structure) with x=1.16 that largely resembles that of bulk delta-ZrH2. For yet lower hydrogen contents, the structures are mixed alpha and delta-phases, while sufficient hydrogen loading (x>1) yields a pure {\delta}-phase that is understoichiometric, but thermodynamically stable. The change in the hydrogen content and strain is discussed in relation to the corresponding change of bond lengths, hybridizations, and trends in electrical resistivity.Comment: 17 pages, 7 figure

Electronic Properties and Bonding in ZrHx Thin Films Investigated by Valence-Band X-ray Photoelectron Spectroscopy

The electronic structure and chemical bonding in reactively magnetron sputtered ZrHx (x=0.15, 0.30, 1.16) thin films with oxygen content as low as 0.2 at% are investigated by 4d valence band, shallow 4p core-level and 3d core-level X-ray photoelectron spectroscopy. With increasing hydrogen content, we observe significant reduction of the 4d valence states close to the Fermi level as a result of redistribution of intensity towards the H 1s - Zr 4d hybridization region at about 6 eV below the Fermi level. For low hydrogen content (x=0.15, 0.30), the films consist of a superposition of hexagonal closest packed metal (alpha-phase)and understoichiometric delta-ZrHx (CaF2-type structure) phases, while for x=1.16, the film form single phase ZrHx that largely resembles that of stoichiometric delta-ZrH2 phase. We show that the cubic delta-ZrHx phase is metastable as thin film up to x=1.16 while for higher H-contents, the structure is predicted to be tetragonally distorted. For the investigated ZrH1.16 film, we find chemical shifts of 0.68 and 0.51 eV towards higher binding energies for the Zr 4p3/2 and 3d5/2 peak positions, respectively. Compared to the Zr metal binding energies of 27.26 and 178.87 eV, this signifies a charge-transfer from Zr to H atoms. The change in the electronic structure, spectral line shapes, and chemical shifts as function of hydrogen content is discussed in relation to the charge-transfer from Zr to H that affects the conductivity by charge redistribution in the valence band.Comment: 11 pages, 6 figure

Application of hybridization control probe to increase accuracy on ligation detection or minisequencing diagnostic microarrays

<p>Abstract</p> <p>Background</p> <p>Nucleic acid detection based on ligation reaction or single nucleotide extension of ssDNA probes followed by tag microarray hybridization provides an accurate and sensitive detection tool for various diagnostic purposes. Since microarray quality is crucial for reliable detection, these methods can benefit from correcting for microarray artefacts using specifically adapted techniques.</p> <p>Findings</p> <p>Here we demonstrate the application of a per-spot hybridization control oligonucleotide probe and a novel way of computing normalization for tag array data. The method takes into account the absolute value of the detection probe signal and the variability in the control probe signal to significantly alleviate problems caused by artefacts and noise on low quality microarrays.</p> <p>Conclusions</p> <p>Diagnostic microarray platforms require experimental and computational tools to enable efficient correction of array artefacts. The techniques presented here improve the signal to noise ratio and help in determining true positives with better statistical significance and in allowing the use of arrays with poor quality that would otherwise be discarded.</p

Indexing, Unchained

Improved toughness is one of the central goals in the development of wear-resistant coatings. Previous studies of toughness in transition metal nitride alloys have addressed the effects of chemical composition in these compounds. Herein, we use density functional theory to study the effects of various metal sublattice configurations, ranging from fully ordered to fully disordered, on the mechanical properties of VM2N and TiM2N (M2 = W, Mo) ternary alloys. Results show that all alloys display high incompressibility, indicating strong M-N bonds. Disordered atomic arrangements yield lower values of bulk moduli and C11 elastic constants, as well as higher values of C44 elastic constants, compared to ordered structures. We attribute the low C44 values of ordered structures to the formation of fully-bonding states perpendicular to the applied stress. We find that the ductility of these compounds is primarily an effect of the increased valence electron concentration induced upon alloying