In this paper the low temperature deposition of nanocrystalline and ultrananocrystalline diamond (UNCD) films is compared and discussed. NCD films were prepared by hot filament chemical vapor deposition from a 1% CH4/H2 mixture, while microwave plasma chemical vapour deposition was used to deposit UNCD films from a mixture of 17% CH4/N2. The resulting films have been thoroughly characterized concerning their morphology and structure by scanning electron microscopy and concerning their crystalline properties by X‐ray diffraction. The composition was analyzed by X‐ray photoelectron spectroscopy (XPS), whereas XPS and Raman spectroscopy were applied to get information on the bonding structure of the films. The most important result of this study is that the composition, structure, morphology, and bonding environment of UNCD hardly change if the deposition temperature is lowered from 770 to 530 °C or even 450 °C. In contrast, there are drastic changes of the nature of NCD films if the temperature is reduced to 700 °C or even lower. Interestingly, the sp2/sp3 ratio of the NCD films remains low and constant in the temperature range investigated. Rather, the nature of the sp2 grain boundary material undergoes drastic changes if the temperature is lowered below 700 °C. In addition, the films become inhomogeneous on a micrometer (not nanometer) scale. Possible reasons for these observations will be discussed throughout the paper.

Thin boron-doped nanocrystalline diamond (NCD) films have been prepared by microwave plasma enhanced chemical vapour deposition (MPCVD) and used as platforms for grafting of photosensitizer (manganese phthalocyanine, Mn-Pc). The surface of the as-grown films is H-terminated; in order to modify it and study the influence of the termination on the attachment of Mn-Pc the NCD films were subjected to O 2 plasma or NH 3 /N 2 plasma treatments. Contact angle measurements and XPS results showed a successful exchange of the surface termination with OH-or NH 2 -groups. Manganese phthalocyanine molecules were grafted on the NCD surfaces with different terminations, after which each sample was subsequently characterized by XPS and Raman spectroscopy. Finally, the NCD/Mn-Pc samples were used for the preparation of electrodes which were tested in an electrochemical cell with a Pt counter electrode and an Ag/AgCl reference electrode; phosphate buffered saline was used as electrolyte. The characteristics of the electrodes were measured by cyclic voltammetry (CV) and open circuit potential (OCP) in dark and under illumination with a light-emitting diode (LED) operating at 770 nm (a wavelength close to the absorption maximum of Mn-Pc). The first results indicated that after plasma modifications NCD surfaces are suited for Mn-Pc grafting.

Diamond nanopillars with diameters of 1 mm down to 50 nm have been fabricated from two types of diamond thin films, namely nanocrystalline diamond (NCD) and ultrananocrystalline diamond (UNCD) using electron beam lithography (EBL) and reactive ion etching (RIE) in an inductively coupled oxygen plasma (ICP). Aim of the study was to investigate the suitability of these pillars to incorporate nitrogen-vacancy (NV) color centers for applications in quantum information technology (QIT). The first part of the investigation is devoted to a characterization of the pillars, their shape, size, and properties.The second part of this investigation concerns the optical properties of NCD and UNCD nanopillars and the incorporation of NV centers within them. Among others, fluorescence mapping and photoluminescence measurements have been employed for this purpose. It turned out that NCD pillars are quite promising for the applications in QIT envisioned. At the present time, the opposite is the case for UNCD pillars. The reasons for these differences will be discussed on the basis of the differences of the two materials NCD and UNCD.

International audienceSilver (Ag) wire arrays were recently introduced as efficient x-ray radiators and have been shown to create L-shell plasmas that have the highest electron temperature (>1.8 keV) observed on the Zebra generator so far and upwards of 30 kJ of energy output. In this paper, results of single planar wire arrays and double planar wire arrays of Ag and mixed Ag and Al that were tested on the UNR Zebra generator are presented and compared. To further understand how L-shell Ag plasma evolves in time, a time-gated x-ray spectrometer was designed and fielded, which has a spectral range of approximately 3.5–5.0 Å. With this, L-shell Ag as well as cold Lα and Lβ Ag lines was captured and analyzed along with photoconducting diode (PCD) signals (>0.8 keV). Along with PCD signals, other signals, such as filtered XRD (>0.2 keV) and Si-diodes (SiD) (>9 keV), are analyzed covering a broad range of energies from a few eV to greater than 53 keV. The observation and analysis of cold Lα and Lβ lines show possible correlations with electron beams and SiD signals. Recently, an interesting issue regarding these Ag plasmas is whether lasing occurs in the Ne-like soft x-ray range, and if so, at what gains? To help answer this question, a non-local thermodynamic equilibrium (LTE) kinetic model was utilized to calculate theoretical lasing gains. It is shown that the Ag L-shell plasma conditions produced on the Zebra generator at 1.7 maximum current may be adequate to produce gains as high as 6 cm−1 for various 3p → 3s transitions. Other potential lasing transitions, including higher Rydberg states, are also included in detail. The overall importance of Ag wire arrays and plasmas is discussed

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Nitrogen‐vacancy (NV) centers were incorporated during hot filament chemical vapor deposition of diamond nanocrystallites and nanocrystalline diamond (NCD) films. From the latter nanopillars with different diameters were prepared applying electron beam lithography and inductively coupled plasma reactive ion etching. The deposition of either single crystallites or closed films was controlled by the nucleation density on the silicon substrates and the process duration. Optical investigations revealed the presence of ensembles of color centers in both nanostructures. An enhancement of the fluorescence emission by an order of magnitude was observed after the structuring of the NCD films.