Atomic-sized fluorescent defects in diamond are widely recognized as a promising solid state platform for quantum cryptography and quantum information processing. For these applications, single photon sources with a high intensity and reproducible fabrication methods are required. In this study, we report a novel color center in diamond, composed of a germanium (Ge) and a vacancy (V) and named the GeV center, which has a sharp and strong photoluminescence band with a zero-phonon line at 602 nm at room temperature. We demonstrate this new color center works as a single photon source. Both ion implantation and chemical vapor deposition techniques enabled fabrication of GeV centers in diamond. A first-principles calculation revealed the atomic crystal structure and energy levels of the GeV center.

The electric field inside semiconductor devices is a key physical parameter that determines the properties of the devices. However, techniques based on scanning probe microscopy are limited to sensing at the surface only. Here, we demonstrate the direct sensing of the internal electric field in diamond power devices using single nitrogen-vacancy (NV) centers. The NV center embedded inside the device acts as a nanoscale electric field sensor. We fabricated vertical diamond p-i-n diodes containing the single NV centers. By performing optically detected magnetic resonance measurements under reverse-biased conditions with an applied voltage of up to 150 V, we found a large splitting in the magnetic resonance frequencies. This indicated that the NV center senses the transverse electric field in the space-charge region formed in the i-layer. The experimentally obtained electric field values are in good agreement with those calculated by a device simulator. Furthermore, we demonstrate the sensing of the electric field in different directions by utilizing NV centers with different N-V axes. This direct and quantitative sensing method using an electron spin in a wide-band-gap material provides a way to monitor the electric field in operating semiconductor devices.

We report the formation of perfectly aligned, high-density, shallow nitrogen vacancy (NV) centers on the Perfectly aligned shallow ensemble NV centers indicated a high Rabi contrast of approximately 30 % which is comparable to the values reported for a single NV center. Nanoscale NMR demonstrated surfacesensitive nuclear spin detection and provided a confirmation of the NV centers depth. Single NV center approximation indicated that the depth of the NV centers was approximately 9-10.7 nm from the surface with error of less than ±0.8 nm. Thus, a route for material control of shallow NV centers has been developed by step-flow growth using a CVD system. Our finding pioneers on the atomic level control of NV center alignment for large area quantum magnetometry. 6,7 . A fundamental limitation of an NV center based magnetometer is the material control required to confine the NV center in the vicinity (<10 nm) of the substrate surface with a high magnetic sensitivity.Previous studies that examined shallow NV centers focused on either a high-density ensemble for twodimensional large area imaging or a single NV center for high contrast and high coherent time to obtain a minimal detection volume using nanoscale NMR. However, it was found necessary to combine spatial localization of a NV centers with alignment, high density, and a long spin coherence time (T2) to obtain high magnetic sensitivity. The alignment of NV centers in an ensemble is the key to accomplish high contrast while maintaining high signal to noise ratio for high magnetic sensitivity with low accumulation time. In this regard, low energy ion implantation is the most common technique utilized for the production of NV centers in the vicinity of a surface 8 . However, this methodology suffers from large depth dispersion (>10 nm) of the NV centers due to ion straggling and channeling effects 9,10 . Additionally, high-density surface defects formed during implantation affect the spin coherence time and the ensembles show a random orientation with this technique 12,13,14 . Existing studies include reports of CVD growth that demonstrated a narrow distribution in the confinement of NV centers in the vicinity of a surface 11 and their atomic alignment on (100), (110), (113), and (111) substrates for the formation of thick diamond films 14,15,16,17,18,19,20 . Nearly all previous studies have focused on either low density NV centers (<10 13 cm -3 3 ) in the vicinity of a surface with no alignment 21,22,23 or the formation of NV ensembles with alignment in bulk.In this paper, the formation of a perfectly aligned high-density shallow NV center film for surfacesensitive detection of nuclear spin has been demonstrated. Results obtained from SIMS measurement combined with an effective depth obtained from nanoscale NMR measurement confirms presence of shallow NV center approximately 9-10.7 nm from surface with error of less than ±0.8 nm. The results of this study offer a path toward controlling the alignment of shallow NV center ensembles.In this study, NV-containing d...

Selectively aligning a nitrogen-vacancy (NV) ensemble in diamond is an important technique for obtaining a high-sensitivity magnetic sensor. Nitrogen-doped diamonds were grown on (111) substrates by microwave plasma chemical vapor deposition to perform the selective alignment of high-density NV ensembles, yielding perfectly aligned NV ensembles along the [111] direction with a density greater than 1016 cm−3 and a spin relaxation time of 2 µs. Such alignment results in a high signal contrast with an optical magnetic resonance close to the typical value reported with an isolated NV center. These results indicate the possibility of achieving a high sensitivity through the selective alignment of NV ensembles.

Fluorinated graphene has the possibility to achieve unique properties and functions in graphene. We propose a highly controlled fluorination method utilizing fluorine radicals in Ar/F2 plasma. To suppress ion bombardments and improve the reaction with fluorine radicals on graphene, the substrate was placed “face down” in the plasma chamber. Although monolayer graphene was more reactive than bilayer, fluorination of bilayer reached the level of ID/IG ∼ 0.5 in Raman D peak intensity at 532 nm excitation. Annealing fluorinated samples proved reversibility of radical fluorination for both mono- and bi-layer graphenes. X-ray photoelectron spectroscopy showed the existence of carbon-fluorine bonding.