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In this paper, memory devices integrating a double layer of silicon nanocrystals (Si-ncs) as a trapping medium and a HfAlO-based control dielectrics are presented. We will show that the use of two stacked Si-nc layers significantly improves the memory window compared with the single Si-nc layer devices, without introducing anomalies on the charging dynamics. Then, we also evaluate the potential use of a hybrid Si-nc double-layer/SiN layer charge trapping stack. These devices show a good memory window in a Fowler-Nordheim (FN)/FN mode and a good retention (>; 3 V after ten years) with small activation energy (0.35 eV up to 200 °C), thus showing promise for future high-temperature memory applications. A model implying valence-band electron tunneling and a floating-gate-like approximation is used to explain the memory window improvement of the Si-nc double-layer memory devices.

Thin (50 nm) erbium implanted silicon rich oxide films suitable for slot waveguides applications have been produced and studied by means of optical spectroscopy and structural characterisation techniques. Comparison between different deposition techniques in terms of light emitting properties of erbium ions is presented. Special attention is given to the efficiency improvement of the energy transfer from silicon nanoclusters to erbium ions where the type of annealing treatment is proven to be of crucial importance.

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 Er3+ in SiO 2 or Er3+ 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/cm2 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. © 2013 IOP Publishing Ltd., This work was supported by the Spanish Ministry of Science through the project LASSI (TEC2009-08359), by the EC through the project ICT-FP7-224312 HELIOS and by Italy–Spain integrated actions. D N-U is grateful for the financial support of AGAUR through the Beatriu de Pinòs program.

International audience; In this work, a detailed study of the physical mechanisms governing the Source Side Injection programming in ultra-scaled (down to 20nm) SiN split-gate memories is presented. Experimental measurements coupled to static and dynamic TCAD simulations are shown. In particular, we claim that adjusting the select gate voltage in moderate inversion allows for the optimization of the compromise between high electron injection and limited consumption. Then, we show that scaling the dimensions of the select gate can induce a higher consumption, while scaling the memory gate leads to lower programming energy (

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.

The electroluminescence (EL) at 1.54νm of metaloxidesemiconductor (MOS) devices with Er 3+ ions embedded in the silicon-rich silicon oxide (SRSO) layer has been investigated under different polarization conditions and compared with that of erbium doped SiO 2 layers. EL time-resolved measurements allowed us to distinguish between two different excitation mechanisms responsible for the Er 3+ emission under an alternate pulsed voltage signal (APV). Energy transfer from silicon nanoclusters (Si-ncs) to Er 3+ 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 Er 3+ ions. On the contrary, direct impact excitation of Er 3+ by hot injected carriers starts at the FowlerNordheim injection threshold (above 5MVcm 1) and dominates for high-field APV excitation.

International audience; In this work, split-gate charge trap memories with electrical gate length down to 20nm are presented for the 1 st time. Silicon nanocristals (Si-ncs), or silicon nitride (Si 3 N 4) and hybrid Si-nc/SiN based split-gate memories, with SiO 2 or Al 2 O 3 control dielectrics, are compared in terms of program erase and retention. Then, the scalability of split-gate charge trap memories is studied, investigating the impact of gate length reduction on the memory window, retention and consumption. The results are analyzed by means of TCAD simulations.

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.

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.

International audience; Alumina layers deposited by Atomic Layer Deposition followed by Rapid Thermal anneal were characterized. We found that the crystallization of alumina in γ-phase occurs between 700 and 850°C. Optical band gap, stress and density were found to increase upon crystallization Hydrogen content in alumina was characterized by ToF-SIMS and infrared spectroscopy. We found that annealing ambience has a strong influence on hydrogen concentration: oxygen favors hydrogen desorption from alumina. Finally, charge trapping in alumina was characterized by C(V) measurements. A strong correlation between hydrogen concentration and trapping was established.

We report an ultrafast (

International audience; In this work, we present an experimental and theoretical study of nitride-trap devices with a HTO/Al$_2$O$_3$ bi-layer blocking oxide. Such (Silicon/Alumina/HTO/Nitride/Oxide/Silicon) SAONOS devices are compared with standard (Silicon/HTO/Nitride/Oxide/Silicon) SONOS and (Silicon/Alumina/Nitride/Oxide/Silicon) SANOS memories. The role of the different layers (blocking oxide and control gate) is deeply analyzed, focusing on their impact on memory performance and reliability. Then, a semi-analytical model is developed , which provides a good understanding of the physical mechanisms at the origin of program/erase characteristics.

International audience; In this paper we show for the 1 st time that Silicon nanocrystal (Si-ncs) memories with high-k (HfO2, Al2O3 and HfAlO) interpoly dielectrics (IPD) can offer excellent behaviour in the Fowler-Nordheim regime, with great relevance for future sub-45nm NAND memory generations. We significantly advance the state-of-the-art by showing a strict correlation between the different IPD properties (high-k dielectric constants, leakage currents) and the performance obtained on memory transistors down to 90nm gate lengths. In particular the results demonstrate that HfAlO IPDs combine the fast p/e and good 10 5 cycles endurance behaviour of HfO2 and the long retention of Al2O3 with no activation up to 125°C. Then, in order to boost the memory window, we also integrated a hybrid Si-nc/SiN layer floating gate, with a HfAlO based IPD. It is shown that a 6V Vth can be achieved, with good retention and cycling behaviours. Finally, a physical model of Si-nc memories is introduced which explains the impacts of IPD characteristics on memory performance. Introduction The large success of mobile equipment is leading to a dramatic increase of the market for NAND Flash, key devices for mass data storage [1]. Discrete trap memories, such as TANOS [2] and Si-nc memories [3,4] are one of the most suitable candidates to push integration density further beyond the 45nm node, because of their good scalability, robustness against SILC and low floating gate (FG) to floating gate coupling. In particular, Si-nc memories offer the potential of better data-retention at high temperature (the stored electrons being trapped in the Si-nc energy conduction band, rather than in temperature-activated deep traps of nitride), as well as mitigated lateral charge migration (the Si-ncs being isolated from one to the other by silicon dioxide rather than nitride). However, up to now, Si-nc memories have always shown poor FN program/erase characteristics, due to the small Si-nc/control gate coupling. In order to overcome this issue, engineering of the tunnel dielectric and/or IPD [5, 6] is necessary. In particular, in this paper, we present for the 1 st time to our knowledge an exhaustive experimental and theoretical study of Si-nc memories where the conventional HTO or oxide/nitride/oxide (ONO) interpoly dielectric is replaced by HfO2, Al2O3 or HfAlO based IPD. Excellent performance and clear correlations between the device electrical results and the IPD material properties are shown. We also suggest how to solve another issue of Si-nc devices, which makes them poorly interesting for multi-level NAND applications, i.e. the relatively small programming window. As a possible solution we propose the addition of a thin SiN layer over the Si-ncs, which allows for a significant increase of the memory window. Our approach is widely validated through in-depth analysis of Si-nc memories with HfO2, Al2O3 or HfAlO IPD, based on several material results, electrical data on memory transistors, physical modelling and TCAD three-dimensional simulations.

Complementary Metal Oxide Semiconductor (CMOS) down‐scaling leads to a dramatic reduction of the gate dielectric thickness for the isolation efficiency. The properties of hafnium aluminium oxide (HfAlO) are investigated as an alternative to conventional SiO2 as it exhibits the desirable characteristics of a high dielectric constant, a wide bandgap and good thermal stability with silicon. In this study, we show that complementary characterization techniques can be used to tune the deposition parameters to get optimized high‐κ dielectrics since the advanced capabilities of the characterization protocols and configurations allow analysis of few nanometer thick layers.

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.

We report on wavelength conversion through four-wave-mixing in silicon slot-waveguides with embedded silicon nanocrystals. The combination of strong optical confinement and Si:nc nonlinearity provides a huge waveguide nonlinear coefficient γ = 1100 W-1.m-1. Moreover, the improvement in the fabrication procedure allowed a loss reduction with respect to previous reported structures, enabling the achievement of an extreme value for the conversion efficiency which represents the best result ever reported in the scientific literature.

In order to study and monitor rates of rooting, callusing and survival, small diameter stem cuttings (less than 0.4 cm) with eight nodes (12–14 cm long) were taken from trees in the field at different times of the year in tests with small batches of cuttings. Among the four tested substrates, well drained crushed basalt powder placed on a bed of gravel was the best rooting medium. Rooting was generally poor or even non-existent with this type of cutting, but the presence of leaves both promoted rooting and significantly (using Chi square test) improved survival of the cutting. Four leaves were sufficient to assure the necessary metabolic functions. Only stem cuttings collected during the rainy season gave roots and then, only when hormonal treatments were applied to the cuttings. 8%-IBA resulted in significantly better rooting than did 2%-IBA, 0.2%-NAA and 1%-IAA. With 8%-IBA, the rate of rooting varied between 50 and 70% for leafy cuttings collected in the rainy season. Hormonal treatments had a significant effect on the survival rate of the stem cuttings during the two months observation period. Further investigations are being conducted with different types of cuttings.

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.

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.

We present a electroluminescence (EL) study of the Si-rich silicon oxide (SRSO) LEDs with and without Er 3+ ions under different polarization schemes: direct current (DC) and pulsed voltage (PV). The power efficiency of the devices and their main optical limitations are presented. We show that under PV polarization scheme, the devices achieve one order of magnitude superior performance in comparison with DC. Time-resolved measurements have shown that this enhancement is met only for active layers in which annealing temperature is high enough (>1000 °C) for silicon nanocrystal (Si-nc) formation. Modeling of the system with rate equations has been done and excitation cross-sections for both Si-nc and Er 3+ ions have been extracted.