Silicon-rich Oxide Research Articles

Improvement on the onset voltage for electroluminescent devices based in a SiOx/SiOy bilayer obtained by sputtering

Abstract This work is focused on the composition, optical and electroluminescent properties of silicon rich oxide (SiOx, x < 2) films monolayers and bilayers (SiOx/SiOy) deposited by Sputtering with silicon excess between 6.2 to 10.7 at.% were deposited on p-type (100) silicon substrates. As-deposited SiOx films emit a broad photoluminescence (PL) band where the maximum peak shifts from 420 to 540 nm as the Si-excess increases from 6.2 to 10.7 at.%, respectively. The PL intensity strongly increases and the main PL peak shifts to the red region when the SiOx films are thermally annealed. The PL emission band was dependent on silicon excess and the presence of Si-O bonds defects working as emission centers. MOS-like devices were fabricated (N+ polysilicon was used as top contact and aluminum as bottom contact) to study the EL of SiOx monolayers and SiOx/SiOy bilayers. It was found that the required voltage to obtain EL was reduced when SiOx/SiOy bilayers were used in light emitting capacitors (BLECs) as compared to those with SiOx monolayers.

Achieving white electroluminescence and low current consumption in devices based on graphene oxide and silicon

This work reports the emission of white electroluminescence (EL) in devices based on silicon. These devices are formed by a heterostructure of porous silicon (PSi), graphene oxide (GO), silicon-rich-oxide (SRO) thin films, and zinc oxide (ZnO) as a transparent conductor oxide (contact). The current consumption in these devices has been reduced by approximately three orders of magnitude compared to the current currents commonly reported for electroluminescent devices. The white EL emission is corroborated by the EL spectra, which are very broad (from 400 to 750 nm) and are attributed to the different nanostructured defects present in the materials that make up the heterostructures. The devices exhibited EL only in negative bias. According to our analysis of the I–V curves, the space-charge limited current conduction mechanism is the dominant carrier conduction mechanism in the region where the EL takes place. The electroluminescence exhibited by these devices starts at a current of 1.1 μA and is the entire area electroluminescent at approximately 3 μA reaches its maximum value at 9 μA. We demonstrated that producing LEDs on a Si substrate can result in significant energy savings.

Artificial optoelectronic synapses based on capture layer of silicon rich oxides

The optoelectronic bionic synapse, as a new memory device with integrated storage and calculation, can respond to light stimulation, for use in the bio-visual system. These also have the advantages of large bandwidth, low crosstalk, and low power consumption. In this study, amorphous silicon (Si) films were annealed at 200 °C, 300 °C, 400 °C, and 500 °C, respectively. SiOx defects were introduced at their interfaces and optoelectronic synapses, resulting in the formation of SiOx/a-Si/P++-Si. X-ray photoelectron spectroscopy was used to characterize the effect of different annealing temperatures on the composition of SiOx. The devices successfully simulated a series of important synaptic functions, including excitatory postsynaptic currents, paired-pulse facilitation, short-term to long-term memory conversion, learning-experience behaviors, etc. The devices prepared under different annealing processes had different memory effects. Based on this, a 3 × 3 array of image memory optoelectronic synapse was prepared to simulate the human brain short-term, long-term, and after-repeated memory state, of human beings. Finally, based on the changes in the mode of Si and oxygen binding and the activation energy of oxygen, the reason for the differences in the memory properties of synaptic devices prepared at different annealing temperatures could be explained.

Mechanism and properties of all-optical switching constructed from 1D symmetric defect ring optical waveguide network

In this paper, barium fluoride (BaF2) and bismuth doped silicon-rich silicon dioxide (Bi-doped Si-rich SiO2) are used for designing a novel pump-free ultracompact ultrahigh efficiency all-optical switching constructed from a photonic band gap (PBG) structure, the one-dimensional (1D) symmetric defect ring optical waveguide network (SDROWN) with integer-broken waveguide length ratio. The ultralow threshold control energy of our designing all-optical switching is 1.24556 × 10−25J, which makes the switching be pump-free. The transverse and longitudinal feature sizes of the switching are, respectively, 160 nm and 270 nm, which arrive at the level of the best reported results and makes the switching may realize intense integration. The ultrahigh switching efficiency arrives at 8.69565 × 107 and is more than 2 orders of magnitude larger than those of other kinds of all-optical switchings. The switching time is nearly 116fs, which arrives at the level of the best reported results. On the other hand, this technique may provide the probability for solving the four contradictions/difficulties in the designing of practical on-chip all-optical switching. It may deepen people's knowledge on PBG structures and provide new scientific bases for the designing of practical on-chip all-optical switching.

Numerical Simulation of an Inverted Perovskite Solar Cell Using a SiOx Layer as Down-Conversion Energy Material to Improve Efficiency and Stability

Inverted perovskite solar cells (PSCs) have gained much attention due to their low hysteresis effect, easy fabrication, and good stability. In this research, an inverted perovskite solar cell ITO/PEDOT:PSS/CH3NH3PbI3/PCBM/Ag structure was simulated and optimized using SCAPS-1D version 3.3.10 software. The influence on the device of parameters, including perovskite thickness, total defect density, series and shunt resistances, and operating temperature, are discussed and analyzed. With optimized parameters, the efficiency increased from 13.47% to 18.33%. Then, a new SiOx/ITO/PEDOT:PSS/CH3NH3PbI3/PCBM/Ag device was proposed which includes a silicon-rich oxide (SiOx) layer. This material was used as the down-conversion energy material, which converts high-energy photons (ultraviolet UV light) into low-energy photons (visible light), improving the stability and absorption of the device. Finally, with SiOx, we obtained an efficiency of 22.46% in the simulation. Therefore, the device with the SiOx layer is the most suitable as it has better values for current density–voltage output and quantum efficiency than the device without SiOx.

A comprehensive calibration of integrated magnetron sputtering and plasma enhanced chemical vapor deposition for rare-earth doped thin films

A new integrated deposition system taking advantage of magnetron sputtering and electron cyclotron-plasma enhanced chemical vapour deposition (IMS ECR-PECVD) is presented that mitigates the drawbacks of each fabrication system. This tailor-made system provides users with highly homogeneous and pure thin films with less undesired hydrogen and well-controlled rare-earth concentration compared to existing methods of rare-earth doping, such as metalorganic powders, sputtering, and ion implantation. We established the first comprehensive report on the deposition parameters of argon flow and sputtering power to achieve desired rare-earth concentrations in a wide composition range of terbium (Tb) doped-silicon oxide (Tb:SiOx) matrices including silicon-rich (x < 2), oxygen-rich (x > 2), and stoichiometric silicon oxide (x = 2). The deposition parameters to fabricate crystalline structure (Tb2Si2O7) in oxygen-rich samples are reported where Tb ions are optically active. IMS ECR-PECVD pushes the solubility limit of the rare-earth dopant in silicon films to 17 at.% for the desired future nanophotonic devices.Graphical

Design of a p-i-n type inverted perovskite solar cell using SiOx as down-conversion material to improve PCE: Simulation and optimization in SCAPS-1D

In this research work, an inverted p-i-n type perovskite solar cell: ITO/PEDOT: PSS/CH3NH3PbI3/PCBM/Au has been simulated and optimized in SCAPS-1D. The optimized parameters in SCAPS-1D that improved solar performance were: perovskite thickness, the total defect density of perovskite, the total defect density of interfaces, series and shunt resistances, and device operating temperature. As a result, the efficiency (PCE) increased to 18.33%. Subsequently, when the silicon-rich oxide (SiOx) material was implemented in the simulation as downconversion energy material on the outside of the cell, a power conversion efficiency (PCE) of 23.7% was obtained. The SiOX film obtained experimentally by sputtering obtained good photoluminescence, absorption coefficient, band gap, and transmittance characteristics before and after thermal annealing. These characteristics have been considered for the proposed device. It is indicated that the inverted perovskite solar cell of type pi-n: SiOx/ITO/PEDOT:PSS/CH3NH3PbI3/PCBM/Au has better J-V output values and EQ quantum efficiency than the perovskite solar cell without SiOx.

Diagnosing Time-Varying Harmonics in Low-k Oxide Thin Film (SiOF) Deposition by Using HDP CVD.

This study identified time-varying harmonic characteristics in a high-density plasma (HDP) chemical vapor deposition (CVD) chamber by depositing low-k oxide (SiOF). The characteristics of harmonics are caused by the nonlinear Lorentz force and the nonlinear nature of the sheath. In this study, a noninvasive directional coupler was used to collect harmonic power in the forward and reverse directions, which were low frequency (LF) and high bias radio frequency (RF). The intensity of the 2nd and 3rd harmonics responded to the LF power, pressure, and gas flow rate introduced for plasma generation. Meanwhile, the intensity of the 6th harmonic responded to the oxygen fraction in the transition step. The intensity of the 7th (forward) and 10th (in reverse) harmonic of the bias RF power depended on the underlying layers (silicon rich oxide (SRO) and undoped silicate glass (USG)) and the deposition of the SiOF layer. In particular, the 10th (reverse) harmonic of the bias RF power was identified using electrodynamics in a double capacitor model of the plasma sheath and the deposited dielectric material. The plasma-induced electronic charging effect on the deposited film resulted in the time-varying characteristic of the 10th harmonic (in reverse) of the bias RF power. The wafer-to-wafer consistency and stability of the time-varying characteristic were investigated. The findings of this study can be applied to in situ diagnosis of SiOF thin film deposition and optimization of the deposition process.

Nanocomposites of Silicon Oxides and Carbon: Its Study as Luminescent Nanomaterials

In this work, hybrid structures formed by nanostructured layers, which contain materials, such as porous silicon (PSi), carbon nanotubes (CNTs), graphene oxide (GO), and silicon-rich oxide (SRO), were studied. The PSi layers were obtained by electrochemical etching over which CNTs and GO were deposited by spin coating. In addition, SRO layers, in which silicon nanocrystals are embedded, were obtained by hot filament chemical vapor deposition (HFCVD) technique. Photoluminescence (PL) spectra were obtained from the hybrid structures with which a comparative analysis was completed among different PL ones. The SRO layers were used to confine the CNTs and GO. The main purpose of making these hybrid structures is to modulate their PL response and obtain different emission energy regions in the PL response. It was found that the PL spectra of the CNTs/SRO and GO/SRO structures exhibit a shift towards high energies compared to those obtained from the PSi layers; likewise, the PSi/CNTs/SRO and PSi/GO/SRO structures show a similar behavior. To identify the different emission mechanisms originated by PSi, GO, CNTs, and SRO, the PL spectra were deconvolved. It was found that the Psi/CNTs/SRO and Psi/GO/SRO structures exhibit a PL shift in respect to the PSi layers, for this reason, the modulation of the PL emission of the structures makes these hybrid structures promising candidates to be applied in the field of photonic and electroluminescent devices.

Superior Effect of Si Doping on Interfacial Reaction of LiPON Solid Electrolyte for the Silicon-Rich Oxide (SiO1/2) Anode in All-Solid-State Batteries: A First-Principles Prediction

Silicon oxide is considered an alternative silicon anode for lithium-ion batteries, possessing high lithium capacity and excellent cycling performance. However, the application of silicon oxide in a solid-state lithium battery is still not reported; exploring the atomic-scale mechanism at its interface with the solid-state electrolyte is critical for further study. In this work, atomic-scale electrochemistry of Si-, B-, and C-doped LiPON solid electrolytes for the silicon-rich oxide (SiO1/2) electrode is explored by first-principles simulations. Our calculations reveal that the interfacial stability and conductivity are significantly enhanced upon doping of Si in LiPON. The SiO1/2/LiSiPON interface presents the highest adhesion energy and the lowest interface formation energy, suggesting a superior stability of the interface. An obvious shift of the DOS curve and large charge overlap area can be observed for LiSiPON with incorporation of the SiO1/2 layer, which shows a much smaller band gap compared with primitive LiSiPON. Moreover, lithium tends to diffuse along the LiSiPON/SiO1/2 interface, and the doped elements provide a channel for lithium transport due to mutual electrostatic interaction. Our work provides theoretical guidance for designing electrode/SSE interfaces for silicon oxide-based ASSBs.

Characterizing Oxide Inclusions in Welded Lean Duplex Stainless Steels and Their Influence on Impact Toughness

In newly developed 2101 lean duplex stainless steel, oxide inclusions have been detected on welded metal zones after subjecting them to flux-cored arc welding with an E2209T1-1 flux-cored filler metal. These oxide inclusions directly affect mechanical properties of the welded metal. Hence, a correlation requiring validation has been proposed between oxide inclusions and mechanical impact toughness. Accordingly, this study employed scanning electron and high-resolution transmission electron microscopy to assess the correlation between oxide inclusions and mechanical impact toughness. Investigations revealed that the spherical oxide inclusions comprised a mixture of oxides in the ferrite matrix phase and were close to intragranular austenite. The oxide inclusions observed were titanium- and silicon-rich oxides with amorphous structures, MnO with a cubic structure, and TiO2 with an orthorhombic/tetragonal structure, derived from the deoxidation of the filler metal/consumable electrodes. We also observed that the type of oxide inclusions had no strong effect on absorbed energy and no crack initiation occurred near them.

Study of silicon rich oxide light emitter capacitors using textured substrates by metal assisted chemical etching

Mono and multilayer silicon rich oxide light-emitting capacitors (SRO-LEC) were fabricated using both polished and textured Si substrates. The textured substrate surface was treated by metal-assisted chemical etching (MACE) for 10 s and 20 s forming nanoneedles. Monolayer devices fabricated using textured substrates required lower energy to emit light and present at least 40% higher emission intensity than non-textured substrates. On the other hand, multilayer devices fabricated on textured and polished substrates showed that both LECs required similar energy to start the emission, however, after the bias is increased up to 5.5 MV/cm the textured LECs presented 36% higher emission intensity. The evidence shows that the electric field is screened by the nanocrystals in the SRO with Ro = 10 at electric fields lower than 5.5 MV/cm.

MIS-Like Structures with Silicon-Rich Oxide Films Obtained by HFCVD: Their Response as Photodetectors.

MIS-type structures composed of silicon-rich oxide (SRO), thin films deposited by hot filament chemical vapor deposition (HFCVD), show interesting I-V and I-t properties under white light illumination and a response as photodetectors. From electrical measurements, it was found that at a reverse bias of −4 V, the illumination current increased by up to three orders of magnitude relative to the dark current, which was about 82 nA, while the photogenerated current reached a value of 25 μA. The reported MIS structure with SRO as the dielectric layer exhibited a hopping conduction mechanism, and an ohmic conduction mechanism was found with low voltage. I-t measurements confirmed the increased photogenerated current. Furthermore, the MIS structure, characterized by current-wavelength (I-λ) measurements, exhibited a maximum responsivity value at 254 mA/W, specific detectivity (D*) at 2.21 × 1011 cm Hz1/2 W−1, and a noise equivalent power (NEP) of 49 pW at a wavelength of 535 nm. The structure exhibited good switching behavior, with rise and fall times between 120 and 150 ms, respectively. These rise and decay times explain the generation and recombination of charge carriers and the trapping and release of traps, respectively. These results make MIS-type structures useful as photodetectors in the 420 to 590 nm range.

Effect of carbon concentration on optical and structural properties in the transition from Silicon Rich Oxide to SiCxOy films formation

The role of carbon atomic concentration on the transition from Silicon Rich Oxide (SRO) to Silicon Oxicarbide films (SiCxOy) is reported. For this, optical and structural properties were analyzed by Photoluminescence (PL), Micro-Raman, Fourier Transform Infrared (FTIR) and X-Ray Photoelectron Spectroscopy (XPS) measurements. An SRO film with 16.6 at.% of Si-excess and SiCxOy films with carbon concentration from 1.3 to 7.2 at.% were grown by Hot Filament Chemical Vapor Deposition Technique (HFCVD). The SRO film (C = 0 at.%) and SiCxOy films with low carbon atomic concentration (C = 1.3 at.%) exhibited a very low PL emission in the red-infrared region (1.5–1.7 eV) manly attributed to SiO defects which are reduced or annihilated by incorporation of carbon. An increase in carbon atomic concentration greater than 1.3 produces a strong PL emission at white region (3.35–1.72 eV) characteristic of SiCxOy films attributed to radiative defects such as defects associated to Si-related oxygen vacancies (Si-NOVs), Si-related oxygen deficiency centers (Si-ODC) and C-related oxygen vacancies (C-NOVs). In this work it was found that a carbon atomic concentration greater that 1.3 is required to have a high density of these radiative defects. Also, due to the high growth temperature (900 °C) and Si-excess (from 16.6 to 3.9 at.%), we propose the presence of Si nanocrystals (Si–NCs) embedded in both SRO and SiCxOy films with low carbon concentration (SiO2-Like characteristics). Whereas an increase in carbon concentration of 7.2 at. %, Si–NCs precipitation was inhibited in the SiCxOy films.

Effect of the Graded Silicon Content in SRN/SRO Multilayer Structures on the Si Nanocrystals and Si Nanopyramids Formation and Their Photoluminescence Response.

Two multilayer (ML) structures, composed of five layers of silicon-rich oxide (SRO) with different Si contents and a sixth layer of silicon-rich nitride (SRN), were deposited by low pressure chemical vapor deposition. These SRN/SRO MLs were thermally annealed at 1100 °C for 180 min in ambient N2 to induce the formation of Si nanostructures. For the first ML structure (MLA), the excess Si in each SRO layer was about 10.7 ± 0.6, 9.1 ± 0.4, 8.0 ± 0.2, 9.1 ± 0.3 and 9.7 ± 0.4 at.%, respectively. For the second ML structure (MLB), the excess Si was about 8.3 ± 0.2, 10.8 ± 0.4, 13.6 ± 1.2, 9.8 ± 0.4 and 8.7 ± 0.1 at.%, respectively. Si nanopyramids (Si-NPs) were formed in the SRO/Si substrate interface when the SRO layer with the highest excess silicon (10.7 at.%) was deposited next to the MLA substrate. The height, base and density of the Si-NPs was about 2–8 nm, 8–26 nm and ~6 × 1011 cm−2, respectively. In addition, Si nanocrystals (Si-ncs) with a mean size of between 3.95 ± 0.20 nm and 2.86 ± 0.81 nm were observed for the subsequent SRO layers. Meanwhile, Si-NPs were not observed when the excess Si in the SRO film next to the Si-substrate decreased to 8.3 ± 0.2 at.% (MLB), indicating that there existed a specific amount of excess Si for their formation. Si-ncs with mean size of 2.87 ± 0.73 nm and 3.72 ± 1.03 nm were observed for MLB, depending on the amount of excess Si in the SRO film. An enhanced photoluminescence (PL) emission (eight-fold more) was observed in MLA as compared to MLB due to the presence of the Si-NPs. Therefore, the influence of graded silicon content in SRN/SRO multilayer structures on the formation of Si-NPs and Si-ncs, and their relation to the PL emission, was analyzed.

Photoluminescence and Crystal Structure of Eu Doped Silicon Oxide Prepared By Hybrid Sputtering and ECR-PECVD

Silicon based light emitters have attracted a considerable interest due to its potential application in emerging technology in the field of solid-state lightening (SSL), solar cells, light emitting diodes (LEDs) and displays. Sharp and well-defined, 4f transition emission of rare earth (RE) elements drive RE doping to be one of the major approaches for enhancing the optical properties of silicon-based materials and it has drawn a significant attention over the last few decades [1]. Cerium (Ce) and terbium (Tb) correspond to blue and green light emission, respectively, and they have been developed to some extent. However, achieving the red-light emission which attributes to the trivalent europium (Eu) oxidation state is more challenging due to the change between the two oxidation states of Eu (Eu2+ and Eu3+) [2].In this work, a set of Eu doped oxygen rich silicon oxide (ORSO) thin films are fabricated using an integrated magnetron sputtering and electron cyclotron resonance plasma enhanced chemical vapor deposition (IMS-ECR-PECVD) system [3]. Following the deposition, the thin films are subjected to annealing using pure nitrogen (N2) and 95% of nitrogen and 5% of hydrogen (N2+H2) atmospheres and different temperatures ranging from 300 to 1350 °C. Performing the photoluminescence (PL) measurements shows that thin films annealed at elevated temperatures (above 1000 °C) exhibit more intense luminescence compared to the ones annealed at lower temperatures (below 900 °C). At annealing temperatures as low as 300 °C, PL intensity at 615 nm which is corresponding to 5D0 to 7F2 transition of trivalent Eu ion is observed. Furthermore, the effect of hydrogen passivation is investigated (as shown in Figure. 1.a) confirming the passivation resulting in an increase of PL intensity by one order of magnitude.Performing Rutherford backscattering spectroscopy (RBS) it is verified the Eu concentration of the thin films vary from 0.17 at. % to 6.36 at. %. It is observed that through IMS-ERC-PECVD system, the concentration of the RE, in this case Eu, can be controlled by manipulating the deposition parameters while the sputtering power shows the most considerable influence. Variable angle spectroscopy ellipsometry (VASE) is conducted to obtain the refractive index and thickness of the thin films. The incorporation of more hydrogen decreases the refractive index whereas the thickness is inversely proportional to hydrogen increase in the deposited film.X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM) explain the PL behavior for samples annealed at higher temperatures. The formation of EuxSiyOz crystals approves the intense PL emission of samples annealed at elevated temperatures (above 1000 ºC) particularly at 1350 ºC while for the samples annealed at temperatures below 800 °C, the structure remains amorphous (shown in Figure 1.b).

Impact of the gate fabrication process of light emitting capacitors based on silicon-rich oxide: Low voltage electroluminescence

We study the effect of the gate fabrication process on the electro-optical properties of metal-oxide-semiconductor (MOS) capacitors with a silicon-rich oxide (SRO) film and n+ polysilicon (Poly-Si) layer as the active layer and gate electrode, respectively. Two sets of capacitors were fabricated changing the Poly-Si doping process. The first set was doped using a mixture of N2, O2 and PH4 at 1000 °C for 15 min. The second set was similarly doped but an additional re-diffusion process using only N2 and O2 at 1000 ᵒC for 20 min was carried out. The doping step causes diffusion of silicon (Si) atoms from a Poly-Si gate towards the SRO which binds to its microstructure forming Si0, Si2+, Si3+ states while the re-diffusion also causes a diffusion of phosphorus (P) atoms, forming P–Si bonds and generating a restructuring of the SRO. These changes determine the electro-optical properties of devices based on SRO. Capacitors with doped emit full area white electroluminescence (EL) observed a naked eye at ∼27 V (∼7 MV/cm) while capacitors with doped + re-diffusion emit orange-red EL spots at ∼ 6 V (∼1.5 MV/cm).

Computational Simulation of a Hot Filament Chemical Vapor Deposition Process for Depositing SRO Films

In the present report, a two dimensional (2D) model was developed to describe the fluid dynamics, heat and mass transfer of a Chemical Vapor Deposition activated by a Hot Filament (HFCVD) reactor, as well as the chemical generation of the precursor species which are present in the growth of non-stoichiometric silicon rich oxide (SRO) films. The SRO is known for have excellent photo luminescent properties which are useful in optoelectronic applications. This material can be obtained by the HFCVD technique which offers important advantages such as the easily to obtain thin films with diverse structural, compositional and optical characteristics. During deposition is a priority to control key parameters as inlet flow, substrate temperature and pressure so it compels to know previous theoretical information about these parameters which can be obtained by computational simulation. Therefore, by means of commercial Computational Fluid Dynamics (CFD) were solved the continuity, momentum and energy equations in steady state. Also, a thermodynamic equilibrium study of the SiO2(s) + H2 (g) reaction was carried out with the Factsage software. The thermodynamic equilibrium results provide the main chemical species which are present during the deposit process of the SRO films. The 2D model was used to simulate the temperature and velocity distribution of the hydrogen in the deposit process. The theoretical calculated temperatures were compared with those obtained experimentally by thermocouple measurements. From the simulation results, the temperature and gas velocity profiles were obtained at different hydrogen flow levels (50, 75, 100 sccm) and temperature source-substrate distances (5, 6 and 7mm) for a 50 sccm level. SEM micrographs and profilometry measurements disclose that the outlet configuration affects substantially both the thickness and surface uniformity of the SRO films. This parameter was modified to obtain a better quality (thickness and uniformity) and a large deposit area.

Slot Waveguides With Silicon-Rich Materials for Nonlinear Applications

Slot waveguides based on silicon-rich materials are proposed and experimentally demonstrated, which consist of a silicon-rich oxide (SRO) slot layer sandwiched by two silicon-rich nitride (SRN) layers. Measurements show the waveguides have a low propagation loss of ~ 2.2 dB/cm and a 50-μm-radius micro-ring resonator can achieve a loaded quality factor (Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">load</sub> ) of ~ 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> . Four-wave mixing experiments in the slot waveguides reveal a high nonlinearity γ of 16 W <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> of the waveguide and an averaged nonlinear index n <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> of 2.5 x 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-18</sup> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /W of the silicon-rich materials, 10 times larger than that of stoichiometric silicon nitride (Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> ). Supercontinuum generation (SCG) experiments have shown a large fabrication tolerance of such slot waveguides that 1.2 octave spectral broadening in a 1510-nm-wide slot waveguide can be achieved while that is 0.9 octave in a slot waveguide with a width shrinking as large as 220 nm.

Blue Electroluminescence in SRO-HFCVD Films.

In this work, electroluminescence in Metal-Insulator-Semiconductors (MIS) and Metal-Insulator-Metal (MIM)-type structures was studied. These structures were fabricated with single- and double-layer silicon-rich-oxide (SRO) films by means of Hot Filament Chemical Vapor Deposition (HFCVD), gold and indium tin oxide (ITO) were used on silicon and quartz substrates as a back and front contact, respectively. The thickness, refractive indices, and excess silicon of the SRO films were analyzed. The behavior of the MIS and MIM-type structures and the effects of the pristine current-voltage (I-V) curves with high and low conduction states are presented. The structures exhibit different conduction mechanisms as the Ohmic, Poole–Frenkel, Fowler–Nordheim, and Hopping that contribute to carrier transport in the SRO films. These conduction mechanisms are related to the electroluminescence spectra obtained from the MIS and MIM-like structures with SRO films. The electroluminescence present in these structures has shown bright dots in the low current of 36 uA with a voltage of −20 V to −50 V. However, when applied voltages greater than −67 V with 270 uA, a full area with uniform blue light emission is shown.