Split-vacancy color centers in diamonds are promising solid-state platforms for the implementation of photonic quantum technologies. These luminescent defects are commonly fabricated upon low-energy ion implantation and subsequent thermal annealing. Their technological uptake will require the availability of reliable methods for the controlled, large-scale production of localized individual photon emitters. This task is partially achieved by controlled ion implantation to introduce selected impurities in the host material and requires the development of challenging beam focusing or collimation procedures coupled with single-ion detection techniques. We report on the protocol for the direct optical activation of split-vacancy color centers in diamond via localized processing with a continuous-wave laser at mW optical powers. We demonstrate the activation of photoluminescent Mg- and Sn-related centers at both the ensemble and single-photon emitter levels in ion-implanted, high-purity diamond crystals without further thermal processing. The proposed lithographic method enables the activation of individual color centers at specific positions of a large-area sample by means of a relatively inexpensive equipment offering real-time, in situ monitoring of the process.

The Ion Beam Induced Charge (IBIC) technique is widely used to characterize the electronic properties of semiconductor materials and devices. Its main advantage over other charge collection microscopies stems in the use of MeV ion probes, which provide both measurable induced charge signals from single ions, and high spatial resolution, which is maintained along the ion range. It is a fact, however, that the use of low-energy ions in the keV range can provide the IBIC technique with complementary analytical capabilities, that are not available with MeV ions, for example the higher sensitivity to the status, contamination and morphology of the surface and the fact that the induced signal depends on the transport of only one type of charge carrier. This paper outlines the upgrade that was made at the 100 kV ion implanter of the University of Torino, originally installed for material and surface modification, to explore the rather unexplored keV-IBIC field and to assess its potential to characterize semiconductor devices. Finally, we report the first IBIC application of our apparatus, which regards the assessment of the radiation damage of a commercially available silicon photodiode, adopting the IAEA experimental protocol and the relevant interpretative model.

In this study, we inspect and analyse the effect of Al implantation into AlN by conducting confocal microscopy on the ion implanted regions, before and after implantation, followed by an annealing step. The independent effect of annealing is studied in an unimplanted control region, which showed that annealing alone does not produce new emitters. Through tracking individual locations in a lithographically patterned sample, we observe that point-like emitters are created in the implanted regions after annealing. The newly created quantum emitters show anti-bunching under ambient conditions and are spectrally similar to the previously discovered emitters in as-grown AlN.

The recent demonstration of optically active telecom emitters makes silicon a compelling candidate for solid state quantum photonic platforms. Particularly fabrication of the G center has been demonstrated in carbon-rich silicon upon conventional thermal annealing. However, the high-yield controlled fabrication of these emitters at the wafer-scale still requires the identification of a suitable thermodynamic pathway enabling its activation following ion implantation. Here we demonstrate the efficient activation of G centers in high-purity silicon substrates upon ns pulsed laser annealing. The proposed method enables the non-invasive, localized activation of G centers by the supply of short non-stationary pulses, thus overcoming the limitations of conventional rapid thermal annealing related to the structural metastability of the emitters. A finite-element analysis highlights the strong non-stationarity of the technique, offering radically different defect-engineering capabilities with respect to conventional longer thermal treatments, paving the way to the direct and controlled fabrication of emitters embedded in integrated photonic circuits and waveguides.

Nitrogen-Vacancy (NV) centers in diamond are promising systems for quantum technologies, including quantum metrology and sensing. A promising strategy for the achievement of high sensitivity to external fields relies on the exploitation of large ensembles of NV centers, whose fabrication by ion implantation is upper limited by the amount of radiation damage introduced in the diamond lattice. In this works we demonstrate an approach to increase the density of NV centers upon the high-fluence implantation of MeV N2+ ions on a hot target substrate (>550 {\deg}C). Our results show that, with respect to room-temperature implantation, the high-temperature process increases the vacancy density threshold required for the irreversible conversion of diamond to a graphitic phase, thus enabling to achieve higher density ensembles. Furthermore, the formation efficiency of color centers was investigated on diamond substrates implanted at varying temperatures with MeV N2+ and Mg+ ions revealing that the formation efficiency of both NV centers and magnesium-vacancy (MgV) centers increases with the implantation temperature.

Recently, hBN has become an interesting platform for quantum optics due to the peculiar defect-related luminescence properties. In this work, multicolor radiative emissions are engineered and tailored by position-controlled low-energy electron irradiation. Varying the irradiation parameters, such as the electron beam energy and/or area dose, we are able to induce light emissions at different wavelengths in the green–red range. In particular, the 10 keV and 20 keV irradiation levels induce the appearance of broad emission in the orange–red range (600–660 nm), while 15 keV gives rise to a sharp emission in the green range (535 nm). The cumulative dose density increase demonstrates the presence of a threshold value. The overcoming of the threshold, which is different for each electron beam energy level, causes the generation of non-radiative recombination pathways.

The recent demonstration of optically active telecom emitters in silicon has paved the way for realizing industrial-scale silicon-based solid-state quantum photonic platforms. The scientific community has been pursuing the implementation of novel single-photon devices for quantum technology applications by introducing extrinsic impurities inside the silicon lattice upon ion implantation. Here we report the optical characterization through single-photon microscopy of intrinsic W centers in high-purity silicon substrates upon carbon implantation and subsequent rapid thermal annealing. The photoluminescence investigation of their emission properties at cryogenic temperatures allowed us to identify the effects of the post-implantation thermal treatment in the formation of telecom quantum emitters based on interstitial silicon clusters upon the introduction of an extrinsic atomic species.

We report on a systematic optical and structural investigation of the MgV color center in diamond. The results show unique tunable properties of the center making it appealing for its utilization in quantum information processing.

The authors report on the characterization at the single‐defect level of germanium‐vacancy (GeV) centers in diamond produced upon Ge − ion implantation and different subsequent annealing processes, with a specific focus on the effect of high‐pressure‐high‐temperature (HPHT) processing on their quantum‐optical properties. Different post‐implantation annealing conditions are explored for the optimal activation of GeV centers, namely, 900 °C 2 h, 1000 °C 10 h, 1500 °C 1 h under high vacuum, and 2000 °C 15 min at 6 GPa pressure. A systematic analysis of the relevant emission properties, including the emission intensity in saturation regime and the excited state radiative lifetime, is performed on the basis of a set of ion‐implanted samples, with the scope of identifying the most suitable conditions for the creation of GeV centers with optimal quantum‐optical emission properties. The main performance parameter adopted here to describe the excitation efficiency of GeV centers as single‐photon emitters is the ratio between the saturation optical excitation power and the emission intensity at saturation. The results show an up to eightfold emission efficiency increase in HPHT‐treated samples with respect to conventional annealing in vacuum conditions, suggesting a suitable thermodynamic pathway toward the repeatable fabrication of ultra‐bright GeV centers for single‐photon generation purposes.

Nanodiamonds (NDs) gained increasing attention in multiple research areas due to the possibility of tuning their physical and chemical features by functionalizing their surface. This has a crucial impact on their electrical properties, which are essential in applications such as the development of innovative sensors and in the biomedical field. The great interest in electrical conduction in NDs has driven the scientific community to its extensive investigation. The role of various functionalities has been considered and different conduction mechanisms have been proposed. In this work, we reported on a systematic study of the modification of the electrical properties of differently sized NDs, as a function of different thermal treatments in air, hydrogen or inert atmosphere. Samples were electrically characterized in controlled humidity conditions to consider the influence of water on conductivity. NDs electrical properties were interpreted in connection with their surface chemistry and structural features, probed with infrared and Raman spectroscopies. The presence of surface graphite, hydrogen terminations or water adsorbed on hydrophilic oxygen-containing functional groups rendered NDs more conductive. These moieties indeed enabled different conduction mechanisms, which were respectively graphite-mediated conduction, water-induced transfer doping and Grotthus mechanism in surface-adsorbed water. The effect of particles size on conductivity has also been evaluated and discussed. Our experimental findings shed light on the link between surface modifications and electrical properties of NDs, providing at the same time an interpretative key to understanding the effect of particles dimensions.

We report a systematic photoluminescence (PL) investigation of the spectral emission properties of individual optical defects fabricated in diamond upon ion implantation and annealing. Three spectral lines at 620 nm, 631 nm, and 647 nm are identified and attributed to the SnV center due to their occurrence in the PL spectra of the very same single-photon emitting defects. We show that the relative occurrence of the three spectral features can be modified by oxidizing the sample surface following thermal annealing. We finally report the relevant emission properties of each class of individual emitters, including the excited state emission lifetime and the emission intensity saturation parameters.

We provide the first systematic characterization of the structural and photoluminescence properties of optically active centers fabricated upon implantation of 30–100 keV Mg+ ions in synthetic diamond. The structural configurations of Mg-related defects were studied by the electron emission channeling technique for short-lived, radioactive 27Mg implantations at the CERN-ISOLDE facility, performed both at room temperature and 800 °C, which allowed the identification of a major fraction of Mg atoms (∼30 to 42%) in sites which are compatible with the split-vacancy structure of the MgV complex. A smaller fraction of Mg atoms (∼13 to 17%) was found on substitutional sites. The photoluminescence emission was investigated both at the ensemble and individual defect level in the 5–300 K temperature range, offering a detailed picture of the MgV-related emission properties and revealing the occurrence of previously unreported spectral features. The optical excitability of the MgV center was also studied as a function of the optical excitation wavelength to identify the optimal conditions for photostable and intense emission. The results are discussed in the context of the preliminary experimental data and the theoretical models available in the literature, with appealing perspectives for the utilization of the tunable properties of the MgV center for quantum information processing applications.

We report on the systematic characterization of the optical properties of diamond color centers based on Pb impurities. An ensemble photoluminescence analysis of their spectral emission was performed at different excitation wavelengths in the 405–520 nm range and at different temperatures in the 4–300 K range. The series of observed spectral features consist of different emission lines associated with Pb-related defects. Finally, a room-temperature investigation of single-photon emitters under 490.5 nm laser excitation is reported, revealing different spectral signatures with respect to those already reported under 514 nm excitation. This work represents a substantial progress with respect to previous studies on Pb-related color centers, both in the attribution of an articulated series of spectral features and in the understanding of the formation process of this type of defect, thus clarifying the potential of this system for high-impact applications in quantum technologies.

We report on the creation and characterization of the luminescence properties of high-purity diamond substrates upon F ion implantation and subsequent thermal annealing. Their room-temperature photoluminescence emission consists of a weak emission line at 558 nm and of intense bands in the 600–750 nm spectral range. Characterization at liquid He temperature reveals the presence of a structured set of lines in the 600–670 nm spectral range. We discuss the dependence of the emission properties of F-related optical centers on different experimental parameters such as the operating temperature and the excitation wavelength. The correlation of the emission intensity with F implantation fluence, and the exclusive observation of the afore-mentioned spectral features in F-implanted and annealed samples provides a strong indication that the observed emission features are related to a stable F-containing defective complex in the diamond lattice.