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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Diamond is a promising material for the development of emerging applications in quantum optics, quantum information and quantum sensing. The fabrication and characterization of novel luminescent defects with suitable opto-physical properties is therefore of primary importance for further advances in these research fields.In this work we report on the investigation in the formation of photoluminescent (PL) defects upon MeV He implantation in diamond. Such color centers, previously reported only in electroluminescence and cathodoluminescence regime, exhibited two sharp emission lines at 536.5 nm and 560.5 nm, without significant phonon sidebands.A strong correlation between the PL intensities of the above-mentioned emission lines and the He implantation fluence was found in the 10 15 -10 17 cm -2 fluence range. The PL emission features were not detected in control samples, i.e. samples that were either unirradiated or irradiated with different ion species (H, C). Moreover, the PL emission lines disappeared in samples that were He-implanted above the graphitization threshold. Therefore, the PL features are attributed to optically active defects in the diamond matrix associated with He impurities. The intensity of the 536.5 nm and 560.5 nm emission lines was investigated as a function of the annealing temperature of the diamond substrate. The emission was observed upon annealing at temperatures higher than 500 °C, at the expenses of the concurrently decreasing neutral-vacancy-related GR1 emission intensity. Therefore, our findings indicate that the luminescence originates from the formation of a stable lattice defect. Finally, the emission was investigated under different laser excitations wavelengths (i.e. 532 nm and 405 nm) with the purpose of gaining a preliminary insight about the position of the related levels in the energy gap of diamond.

An integrated erbium-based light emitting diode has been realized in a waveguide configuration allowing 1.54 μm light signal routing in silicon photonic circuits. This injection device is based on an asymmetric horizontal slot waveguide where the active slot material is Er(3+) in SiO2 or Er(3+) in Si-rich oxide. The active horizontal slot waveguide allows optical confinement, guiding and lateral extraction of the light for on-chip distribution. Light is then coupled through a taper section to a passive Si waveguide terminated by a grating which extracts (or inserts) the light signal for measuring purposes. We measured an optical power density in the range of tens of μW/cm(2) which follows a super-linear dependence on injected current density. When the device is biased at high current density, upon a voltage pulse (pump signal), free-carrier and space charge absorption losses become large, attenuating a probe signal by more than 60 dB/cm and thus behaving conceptually as an electro-optical modulator. The integrated device reported here is the first example, still to be optimized, of a fundamental block to realize an integrated silicon photonic circuit with monolithic integration of the light emitter.

Abstract:We have fabricated a series of thin (~50 nm) erbium-doped (by ion implantation) silicon-rich oxide films in the configuration that mitigates previously proposed mechanisms for loss of light emission capability of erbium ions. By combining the methods of optical, structural and electrical analysis, we identify the erbium ion clustering as a driving mechanism to low optical performance of this material. Experimental findings in this work clearly evidence inadequacy of the commonly employed optimization procedure when optical amplification is considered. We reveal that the significantly lower erbium ion concentrations are to be used in order to fully exploit the potential of this approach and achieve net optical gain.

Silicon nanocrystals have shown attractive properties for photonic and photovoltaic applications. We demonstrate all-Si light-emitting diodes based on boron-doped Si nanocrystal/c-Si p-n heterojunction structure, which show electroluminescence in the visible/infrared regions. The electroluminescence spectra of these diodes can be modified by changing the quantum confining barriers from SiO2 to Si3N4. Our results are an important demonstration of electroluminescence from boron-doped Si nanocrystals—a wide band gap absorber material for third generation photovoltaics.

High quantum efficiency erbium doped silicon nanocluster (Si-NC:Er) light emitting diodes (LEDs) were grown by low-pressure chemical vapor deposition (LPCVD) in a complementary metal-oxide-semiconductor (CMOS) line. Erbium (Er) excitation mechanisms under direct current (DC) and bipolar pulsed electrical injection were studied in a broad range of excitation voltages and frequencies. Under DC excitation, Fowler-Nordheim tunneling of electrons is mediated by Er-related trap states and electroluminescence originates from impact excitation of Er ions. When the bipolar pulsed electrical injection is used, the electron transport and Er excitation mechanism change. Sequential injection of electrons and holes into silicon nanoclusters takes place and nonradiative energy transfer to Er ions is observed. This mechanism occurs in a range of lower driving voltages than those observed in DC and injection frequencies higher than the Er emission rate. V C 2012 American Institute of Physics. [http://dx