The electroluminescence (EL) at 1.54 μm of metal–oxide–semiconductor (MOS) devices withEr3C ions embedded in the silicon-rich silicon oxide (SRSO) layer has been investigated under different polarization conditions and compared with that of erbium doped SiO2 layers. EL time-resolved measurements allowed us to distinguish between two different excitation mechanisms responsible for the Er3C emission under an alternate pulsed voltage signal (APV). Energy transfer from silicon nanoclusters (Si-ncs) to Er3C is clearly observed at low-field APV excitation. We demonstrate that sequential electron and hole injection at the edges of the pulses creates excited states in Si-ncs which upon recombination transfer their energy to Er3C ions. On the contrary, direct impact excitation of Er3C by hot injected carriers starts at the Fowler–Nordheim injection threshold (above 5 MV cm(-1)) and dominates for high-field APV excitation.

The control of the charge state of nitrogen-vacancy (NV) centers in diamond is of primary importance for the stabilization of their quantum-optical properties, in applications ranging from quantum sensing to quantum computing. In this work buried current-injecting graphitic micro-electrodes were fabricated in bulk diamond by means of a 6 MeV C 3+ scanning micro-beam. The electrodes were exploited to control the variation in the relative population of the negative (NV − ) and neutral (NV 0 ) charge states of sub-superficial NV centers located in the inter-electrode gap regions. Photoluminescence spectra exhibited an electrically-induced increase up to 40% in the NV − population at the expense of the NV 0 charge state, with a linear dependence from the injected current at applied biases smaller than 250V, and was interpreted as the result of electron trapping at NV sites. An * Corresponding author: Tel +39 011 6707306, forneris@to.infn.it, J. Forneris et al., "Electrical control of sub-superficial NV centers in diamond…" p. ! 2 abrupt current increase at ∼300V bias resulted in a strong electroluminescence from the NV0 centers, in addition to two spectrally sharp emission lines at 563.5 nm and 580 nm, not visible under optical excitation and attributed to self-interstitial defects. These results disclose new possibilities in the electrical control of the charge state of NV centers located in the diamond bulk, which are characterized by longer spin coherence times.

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