Substantial developments have been achieved in the synthesis of chemical vapour deposition (CVD) diamond in recent years, providing engineers and designers with access to a large range of new diamond materials. CVD diamond has a number of outstanding material properties that can enable exceptional performance in applications as diverse as medical diagnostics, water treatment, radiation detection, high power electronics, consumer audio, magnetometry and novel lasers. Often the material is synthesized in planar form; however, non-planar geometries are also possible and enable a number of key applications. This paper reviews the material properties and characteristics of single crystal and polycrystalline CVD diamond, and how these can be utilized, focusing particularly on optics, electronics and electrochemistry. It also summarizes how CVD diamond can be tailored for specific applications, on the basis of the ability to synthesize a consistent and engineered high performance product.

In order to improve the performance of existing technologies based on single crystal diamond grown by chemical vapour deposition (CVD), and to open up new technologies in fields such as quantum computing or solid state and semiconductor disc lasers, control over surface and bulk crystalline quality is of great importance. Inductively coupled plasma (ICP) etching using an Ar/Cl gas mixture is demonstrated to remove sub-surface damage of mechanically processed surfaces, whilst maintaining macroscopic planarity and low roughness on a microscopic scale. Dislocations in high quality single crystal CVD diamond are shown to be reduced by using substrates with a combination of low surface damage and low densities of extended defects. Substrates engineered such that only a minority of defects intersect the epitaxial surface are also shown to lead to a reduction in dislocation density. Anisotropy in the birefringence of single crystal CVD diamond due to the preferential direction of dislocation propagation is reported. Ultra low birefringence plates (< 10 -5 ) are now available for intra-cavity heat spreaders in solid state disc lasers, and the application is no longer limited by depolarisation losses. Birefringence of less than 5×10 -7 along a direction perpendicular to the CVD growth direction has been demonstrated in exceptionally high quality samples. † Corresponding author 2 of 25 1.

The gene encoding for Epstein-Barr virus-induced G-protein-coupled receptor 2 (EBI2) is a risk gene for inflammatory bowel disease (IBD). Together with its oxysterol ligand 7α,25-dihydroxycholesterol, EBI2 mediates migration and differentiation of immune cells. However, the role of EBI2 in the colonic immune system remains insufficiently studied. We found increased mRNA expression of EBI2 and oxysterol-synthesizing enzymes (CH25H, CYP7B1) in the inflamed colon of patients with ulcerative colitis and mice with acute or chronic dextran sulfate sodium (DSS) colitis. Accordingly, we detected elevated levels of 25-hydroxylated oxysterols, including 7α,25-dihydroxycholesterol in mice with acute colonic inflammation. Knockout of EBI2 or CH25H did not affect severity of DSS colitis; however, inflammation was decreased in male EBI2 −/− mice in the IL-10 colitis model. The colonic immune system comprises mucosal lymphoid structures, which accumulate upon chronic inflammation in IL-10-deficient mice and in chronic DSS colitis. However, EBI2 −/− mice formed significantly less colonic lymphoid structures at baseline and showed defects in inflammation-induced accumulation of lymphoid structures. In summary, we report induction of the EBI2-7α,25dihydroxycholesterol axis in colitis and a role of EBI2 for the accumulation of lymphoid tissue during homeostasis and inflammation. These data implicate the EBI2-7α,25-dihydroxycholesterol axis in IBD pathogenesis.Mucosal Immunology (2019) 12:733-745; https://doi.

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The photoluminescence of in situ-doped GaN:Er during hydride vapor phase epitaxy was compared to an Er-implanted GaN sample. At 11 K, the main emission wavelength of the in situ-doped sample is shifted to shorter wavelengths by 2.5 nm and the lifetime is 2.1Ϯ0.1 ms as compared to 2.9Ϯ0.1 ms obtained for the implanted sample. The 295 K band edge luminescence of the in situ-doped sample was free of the broad band luminescence centered at 500 nm which dominated the spectrum of the implanted sample. Reversible changes in the emission intensity of the in situ-doped sample upon annealing in a N 2 versus a NH 3 /H 2 ambient indicate the probable role of hydrogen in determining the luminescence efficiency of these samples. © 1998 American Institute of Physics. ͓S0003-6951͑98͒02010-5͔The rare-earth element erbium in the trivalent state (Er 3ϩ ) has received considerable attention since the 4 I 13/2 → 4 I 15/2 transition at 1540 nm coincides with a minimum in loss in silica optical fibers.1 This transition occurs between energy levels within the shielded 4 f electron shell, making the optical transitions of Er 3ϩ sharp, as well as relatively insensitive to temperature and host affects.2 These luminescence properties make erbium-doped semiconductors an appealing material system for application in optoelectronic devices.One problem which plagues the development of a practical erbium-doped semiconductor device is the pronounced temperature quenching of the rare-earth luminescence within most semiconductor hosts. Favennec et al. discovered that quenching of the rare-earth luminescence was reduced in wide band-gap semiconductor hosts.3 This discovery has lead to several investigations of Er-implanted GaN. [4][5][6][7][8][9][10][11][12] GaN is a wide band-gap III-V semiconductor useful as a short wavelength emitter and detector. 13 Previous investigations of Er luminescence in GaN:Er have been promising with most researchers finding only an ϳ50% decrease in photoluminescence intensity over the temperature range 6-300 K. 4,8,9,11 This is a significant improvement over the two-to-three order of magnitude decrease of Er luminescence intensity in GaAs:Er. 2The studies performed on GaN:Er so far have principally focused on Er implanted into GaN. The large mass of the Er implant species limits this technique to the formation of thin layers of GaN:Er with a high amount of residual implantrelated damage. In this letter, we report a photoluminescence study of in situ-doped GaN:Er during hydride vapor phase epitaxy ͑HVPE͒ using elemental Er as the in situ dopant and Er implanted into nominally undoped GaN also grown by HVPE. HVPE is an established technique for GaN growth and is capable of providing high growth rates and thick GaN layers. 13,14 The in situ doping of GaN with Er during HVPE growth should result, therefore, in thick, uniformly doped layers. Low temperature Er 3ϩ luminescence of the in situdoped sample is observed with the peak intensity at 1536.5 nm and an 11 K lifetime of 2.1Ϯ0.1 ms. The Er 3ϩ luminescence was no lon...

Platinum silicide (PtSi) and Pt Schottky contacts on n-GaN have been investigated and compared. The PtSi contacts were formed on n-GaN by annealing a multilayer structure of Pt/Si with the appropriate thickness ratio at 400 °C for 1 h in forming gas. The barrier height of the as-formed PtSi contacts was found to be 0.87 eV capacitance–voltage (C–V), and remained unchanged after further annealing at 400 and 500 °C. Upon annealing at 600 °C for 1 h, the barrier height decreased to 0.74 eV (C–V), but the diodes remained well-behaved. The as-deposited Pt yielded a barrier height of 1.0 eV (C–V). Upon annealing at 400 °C for 1 h, the Pt diodes degraded and most of the diodes did not survive additional annealing at 400 °C for longer times. The electrical measurements and the Rutherford backscattering spectrometry results indicated that PtSi contacts are thermally much more stable than Pt contacts on GaN.

Early pulmonary infection and inflammation result in irreversible lung damage and are major contributors to cystic fibrosis (CF)-related morbidity. An easy to apply and noninvasive assessment for the timely detection of disease-associated complications would be of high value. We aimed to detect volatile organic compound (VOC) breath signatures of children with CF by real-time secondary electrospray ionisation high-resolution mass spectrometry (SESI-HRMS).A total of 101 children, aged 4–18 years (CF=52; healthy controls=49) and comparable for sex, body mass index and lung function were included in this prospective cross-sectional study. Exhaled air was analysed by a SESI-source linked to a high-resolution time-of-flight mass spectrometer. Mass spectra ranging from m/z 50 to 500 were recorded.Out of 3468 m/z features, 171 were significantly different in children with CF (false discovery rate adjusted p-value of 0.05). The predictive ability (CF versus healthy) was assessed by using a support-vector machine classifier and showed an average accuracy (repeated cross-validation) of 72.1% (sensitivity of 77.2% and specificity of 67.7%).This is the first study to assess entire breath profiles of children with SESI-HRMS and to extract sets of VOCs that are associated with CF. We have detected a large set of exhaled molecules that are potentially related to CF, indicating that the molecular breath of children with CF is diverse and informative.

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