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With its outstanding physical properties, single‐crystal diamond is the material of choice for future power electronics and quantum devices. The later application field is based on the optical and spin properties of color centers hosted in diamond lattice. Two synthesis methods are currently developed to grow high‐quality diamond: high pressure and high temperature (HPHT) synthesis and chemical vapor deposition (CVD). Herein, the state of the art of single‐crystal diamond growth by CVD, either starting with diamond substrate (homoepitaxy) or controlling diamond epitaxial nucleation on a foreign substrate (heteroepitaxy) is described. Progress on substrates, dislocation propagation, and reduction of structural defects, doping, upscaling, and applications are reviewed. In light of recent progress, future challenges and the respective roles of homoepitaxial and heteroepitaxial materials in the applications roadmap are discussed. [ABSTRACT FROM AUTHOR]

2D slotted diamond‐based photonic crystals (PhCs) with Q factors up to 6500 are fabricated and optically characterized at 1550 nm in order to probe surface molecular modifications. This study focuses on the simplest surface modifications that can modify the diamond PhC optical properties, namely, hydrogenation and oxidation. Depending on the chemical surface termination, these diamond PhCs exhibit a strong modification of their spectral features. When the surface is tuned from oxidized to hydrogenated, a resonance wavelength shift of the cavity occurs and is accompanied by a decrease of the Q factor. Moreover, experimental evidence is given that this phenomenon is reversible, as the initial value of the Q factor is recovered when the surface is re‐oxidized. This is attributed to the subsurface conductive layer that is due to transfer doping in hydrogenated diamond and which is absent from oxidized diamond. Thanks to 3D finite differences in time domain (FDTD) simulations, an estimate of the effective refractive index of the surface conductive layer at 1.5 μm is given as a function of its thickness. This result highlights the high sensitivity of slotted diamond PhC and the importance of surface control for biosensing with diamond. [ABSTRACT FROM AUTHOR]

Hadron therapy is an innovative mode of radiotherapy (RT) for cancer treatment which enables tumor cells to be more effectively destroyed than conventional RT using photons. The precise knowledge of the lineal energy of particles is used in the field of microdosimetry (MKM model) as a fundamental parameter in the prediction of the relative biological efficiency (RBE) of clinical beams. Based on single‐crystal CVD (scCVD) super‐thin diamond membranes obtained using deep Ar/O2 plasma etching, prototypes of solid‐state microdosimeters for lineal energy measurements are produced at the Diamond Sensors Laboratory of CEA‐LIST. The response of a diamond membrane microdosimeter to single projectiles is investigated in ion microbeams. The microdosimeter is irradiated using a raster scanning method and the charge transport properties of the device are determined with sub‐micron precision by measuring the charge collection efficiency (CCE), the μSVs 3D spatial definition and the pulse‐height spectra. A prototype of this novel microdosimeter is then tested in a 100 MeV therapeutic proton beam at the Institute Curie − Proton Therapy Centre in Orsay. All results effectively demonstrate the great potential for this device to be used for studies of the RBE in clinical applications. Active micro‐sensitive volumes (μSVs) of the tested scCVD diamond membrane based microdosimeter. The colored pixels represent detected ion hits (interactions/pixel) during the ion beam induced charge − IBIC − collection study at AIFIRA facility in CENBG, Bordeaux in France. [ABSTRACT FROM AUTHOR]