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Nitrogen-rich ultra-thin (1–2 nm thick) layers in diamond produced by high-temperature nitrogen ion (N2+) implantation at low N2+ energies studied by in situ x-ray photoelectron spectroscopy are reported. Nitrogen bonding at the subsurface region and its thermal stability, as well as structural defects in polycrystalline diamond (PCD) implanted with 200, 500, and 800 eV N2+ at room temperature (RT) and 600 °C at an ion dose of 4.5 × 1014 ions/cm2, are investigated. Implantation at RT leads to nitrogen bonding at interstitial and substitutional sites in the diamond lattice, which is associated with the C–N/C=N bond, lower intensity of the C≡N (nitrile-like) component associated with nitrogen bonding with carbon defects, and quaternary nitrogen. The relative composition of these chemical states varies with implantation energy, temperature, and post-implantation annealing temperature. Upon annealing the RT implanted layers above 500–600 °C, the interstitial nitrogen converts to substitutional nitrogen. This process competes with nitrogen desorption. The thermal stability of nitrogen increases with implantation energy. Implantation at 600 °C at 800 eV resulted in a significantly lower concentration of nitrile-like bonds and a lower density of structural defects compared to RT implantation at the same energy. These effects are associated with dynamic annealing, which becomes more significant at higher implantation energies. Upon high-temperature implantation, nitrogen mostly populates directly substitutional sites. Nitrogen implantation at low energy and high temperature may be a viable way to nitride diamond surfaces with reduced density of defects where nitrogen is selectively bonded to substitutional sites. Finally, a comparison between nitrogen implantation into PCD and Diamond (100) [Di(100)] surfaces is presented. [ABSTRACT FROM AUTHOR]

Nitrogen vacancy (NV) centers in diamond have emerged in recent years as leading quantum sensors in various modalities. Most applications benefit from shallow NVs, enabling higher sensitivity and resolution. However, near-surface NVs (o20 nm depth) suffer from reduced stability and coherence properties due to additional noise. We demonstrate a novel surface termination technique based on nitrogen plasma under non-damaging conditions, achieving significant improvement in NV optical stability and quantum coherence. X-Ray characterization of the nitrogen-terminated diamond surface suggests limited charge transfer between the NV centers and surface electronic states compared to oxygen-terminated diamond. [ABSTRACT FROM AUTHOR]

This study reports on the influence of nitrogen plasma exposure of H‐diamond (100) on the adsorption of adventitious oxygen, nitrogen bonding, and thermal stability studied by X‐ray photoelectron spectroscopy. The nitrogen‐plasma exposures include microwave (MW) and radio frequency (RF) (at pressures: 3 × 10−2 (damaging) and 7 × 10−2 Torr (nondamaging)) nitrogen plasmas. The largest amount of oxygen ambient adsorption occurs on the damaging RF(N2) (O = 2.8 at%) exposed surface, whereas for MW(N2) (O = 0.8 at%) and nondamaging RF(N2) (O = 1.3 at%) exposed surfaces, a lower oxygen concentration is observed. Also, the highest level of structural damage to the upper atomic layers of the diamond is induced by exposure to the damaging RF(N2), followed by nondamaging RF(N2) and MW(N2). Thus, the near‐surface damage induced by the plasma interaction promotes adventitious oxygen adsorption (in various bonding configurations, including COx and C–NOx). For ambient‐exposed MW(N2)‐processed surface, nitrogen is adsorbed mainly in C–N/C=N state. Whereas for ambient‐exposed nondamaging‐ and damaging RF(N2)‐treated surfaces, nitrogen is bonded in mixed C–N/C=N and C≡N states alongside a small C–NOx component depending on the degree of surface defects. The damaging RF(N2)‐exposed surface exhibits a lower oxygen and nitrogen thermal stability than the other cases. [ABSTRACT FROM AUTHOR]

Deep sub-wavelength (Δ/λ= ~0.22) periodic features are induced uniformly on a nanodiamond (ND) thin film surface using femtosecond (fs) laser irradiation (pulse duration = ~110 fs and central wavelength of 800 nm). The topography of the surface features is controlled by the laser polarization. Orientation of features is perpendicular to laser polarization. Periodicity (spatial periodicity of<λ/4) of the surface features is less than the laser wavelength. This work gives an experimental proof of polarization controlled surface plasmon-fs laser coupling mechanism prompting the interaction between fs laser and solid matter (here ND thin film) which in turn is resulting in the periodic surface features. Scanning electron microscopy in conjunction with micro Raman scattering, X-ray diffraction, and atomic force microscopy are carried out to extract surface morphology and phase information of the laser irradiated regions. This work demonstrates an easy and efficient surface fabrication technique. [ABSTRACT FROM AUTHOR]