J. P. Colonna

Deep-UV Lithography Fabrication of Slot Waveguides and Sandwiched Waveguides for Nonlinear Applications

Slot and sandwiched waveguides with silicon nanocrystals were fabricated by means of industrial microelectronic tools, including DUV lithography. Low loss of 4 dB/cm will pave the way to compact all-optical NOR logic gates.

Erbium emission in MOS light emitting devices: From energy transfer to direct impact excitation

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.

Limit to the erbium ions emission in silicon-rich oxide films by erbium ion clustering

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.

Bipolar pulsed excitation of erbium-doped nanosilicon light emitting diodes

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.

Effect of the annealing treatments on the electroluminescence efficiency of SiO 2 layers doped with Si and Er

We studied the effect of rapid thermal processing and furnace annealing on the transport properties and electroluminescence (EL) of SiO2 layers doped with Si and Er ions. The results show that for the same annealing temperature, furnace annealing decreases the electrical conductivity and increases the probability of impact excitation, which leads to an improved external quantum efficiency. Correlations between predictions from phenomenological transport models, annealing regimes and erbium EL are observed and discussed. (Some figures may appear in colour only in the online journal)

Ultrafast all-optical logic gates with silicon nanocrystal-based slot waveguides

We report an ultrafast (<40ps) all-optical XOR logic gate based on a silicon nanocrystal-based horizontal slot waveguide. The device consists of a Mach-Zehnder interferometer with three input ports, and is driven by ∼200mW peak power.

Ultrafast nonlinear dynamics in silicon nanocrystal-based horizontal slot waveguides

We present the characterization of the nonlinear-dynamics of a CMOS-compatible horizontal-slot waveguide with silicon-nanocrystals, where the temporal behavior of the phase and amplitude of the nonlinear response are simultaneously monitored. These results are complemented with four-wave-mixing measurements.

Electrically pumped Er-doped light emitting slot waveguides for on-chip optical routing at 1.54 μm

Optoelectronic properties of Er3+-doped slot waveguides electrically driven are presented. The active waveguides have been coupled to a Si photonic circuit for the on-chip distribution of the electroluminescence (EL) signal at 1.54 μm. The Si photonic circuit was composed by an adiabatic taper, a bus waveguide and a grating coupler for vertical light extraction. The EL intensity at 1.54 μm was detected and successfully guided throughout the Si photonic circuit. Different waveguide lengths were studied, finding no dependence between the waveguide length and the EL signal due to the high propagation losses measured. In addition, carrier injection losses have been observed and quantified by means of time-resolved measurements, obtaining variable optical attenuation of the probe signal as a function of the applied voltage in the waveguide electrodes. An electro-optical modulator could be envisaged if taking advantage of the carrier recombination time, as it is much faster than the Er emission lifetime.

154µm Er doped light emitting devices: Role of silicon content

Thin erbium implanted silicon rich oxides films have been used as active layer in light emitting devices. Electroluminescence has been observed and analyses as a function of the silicon content.