The Experts below are selected from a list of 5040 Experts worldwide ranked by ideXlab platform
D A Antoniadis - One of the best experts on this subject based on the ideXlab platform.
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design of tunneling field effect transistors using Strained Silicon Strained germanium type ii staggered heterojunctions
IEEE Electron Device Letters, 2008Co-Authors: Osama M Nayfeh, Judy L Hoyt, C N Chleirigh, John Hennessy, L Gomez, D A AntoniadisAbstract:Heterojunction tunneling field-effect transistors (HTFETs) that use Strained-Silicon/Strained-germanium type-II staggered band alignment for band-to-band tunneling (BBT) injection are simulated using a nonlocal quantum tunneling model. The tunneling model is first compared to measurements of gate- controlled BBT in previously fabricated Strained SiGe diodes and is shown to produce good agreement with the measurements. The simulation of the gated diode structure is then extended to study HTFETs with an effective energy barrier of 0.25 eV at the Strained-Si/Strained-Ge heterointerface. As the band alignment, particularly the valence band offset, is critical to modeling HTFET operation, analysis of measured characteristics of MOS capacitors fabricated in Strained-Si/Strained-Ge/relaxed Si0.5Ge0.5 hetero- junctions is used to extract a valence band offset of 0.64 eV at the Strained-Si/Strained-Ge heterointerface. Simulations are used to compare HTFETs to MOSFETs with similar technology parameters. The simulations show that HTFETs have potential for low-operating-voltage (Vdd < 0.5 V) application and exhibit steep subthreshold swing over many decades while maintaining high ON-state currents.
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measurement of enhanced gate controlled band to band tunneling in highly Strained Silicon germanium diodes
IEEE Electron Device Letters, 2008Co-Authors: Osama M Nayfeh, Judy L Hoyt, C N Chleirigh, D A AntoniadisAbstract:Strained Silicon-germanium (Si0.6Ge0.4) gated diodes have been fabricated and analyzed. The devices exhibit significantly enhanced gate-controlled tunneling current over that of coprocessed Silicon control devices. The current characteristics are insensitive to measurement temperature in the 80 K to 300 K range. Independently extracted valence band offset at the Strained Si0.6Ge0.4/Si interface is 0.4 eV, yielding a Si0.6Ge0.4 bandgap of 0.7 eV, which is much reduced compared to that of Si. The results are consistent with device operation based on quantum-mechanical band-to-band (BTB) tunneling rather than on thermal generation. Moreover, simulation of the Strained Si0.6Ge0.4 device using a quantum-mechanical BTB tunneling model is in good agreement with the measurements.
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strain relaxation in patterned Strained Silicon directly on insulator structures
Applied Physics Letters, 2005Co-Authors: R Z Lei, D A Antoniadis, Judy L Hoyt, W Tsai, Ingvar Aberg, T B Oreilly, Henry I Smith, Albert J Paul, M L Green, R HullAbstract:Strain relaxation is studied in Strained Silicon directly on insulator (SSDOI) substrates patterned with nanoscale features. Using interference lithography, biaxially Strained SSDOI substrates with 30nm thick Strained Si on insulator films were patterned into grating structures with 90nm wide stripes, and arrays of 80nm×170nm pillars. The strain profiles of these patterned structures were examined by ultraviolet Raman spectroscopy. Raman analysis of the SSDOI gratings indicates strain relaxation in the 90nm wide stripes, compared to the strain measured in unpatterned portions of the SSDOI wafer. Three-dimensional finite-element modeling of the stress distributions in the grading structures predicts that 95% of the strain is maintained in the direction along the length of the stripes. These simulations are used to decouple the strain components along the width and length of the SSDOI grating structure, inferred from Raman measurements. The results are consistent with substantial stress relaxation across th...
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fabrication of ultra thin Strained Silicon on insulator
Journal of Electronic Materials, 2003Co-Authors: T S Drake, D A Antoniadis, Eugene A Fitzgerald, Arthur J Pitera, R Hull, Ni C Chleirigh, Minjoo L Lee, Dalaver H Anjum, N Klymko, J L HoytAbstract:A bond and etch back technique for the fabrication of 13-nm-thick, Strained Silicon directly on insulator has been developed. The use of a double etch stop allows the transfer of a thin Strained Silicon layer with across-wafer thickness uniformity comparable to the as-grown epitaxial layers. Surface roughness of less than 1 nm was achieved. Raman analysis confirms strain remains in the thin Silicon layers after the removal of the SiGe that induced the strain. Ultra-thin Strained Silicon-on-insulator (SSOI) substrates are promising for the fabrication of ultra-thin body and double-gate, Strained Si metal-oxide semiconductor field-effect transistors (MOSFETs).
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effect of rapid thermal annealing on strain in ultrathin Strained Silicon on insulator layers
Applied Physics Letters, 2003Co-Authors: T S Drake, D A Antoniadis, Eugene A Fitzgerald, Arthur J Pitera, R Hull, Ni C Chleirigh, Minjoo L Lee, Dalaver H Anjum, N Klymko, Judy L HoytAbstract:The fabrication of ultrathin Strained Silicon directly on insulator is demonstrated and the thermal stability of these films is investigated. Ultrathin (∼13 nm) Strained Silicon on insulator layers were fabricated by epitaxial growth of Strained Silicon on relaxed SiGe, wafer bonding, and an etch-back technique employing two etch-stop layers for improved across wafer thickness uniformity. Using 325 nm Raman spectroscopy, no strain relaxation is observed following rapid thermal annealing of these layers to temperatures as high as 950 °C. The thermal stability of these films is promising for the future fabrication of enhanced performance Strained Si ultrathin body and double-gate metal-oxide-semiconductor field-effect transistors.
P Sanchis - One of the best experts on this subject based on the ideXlab platform.
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a sige slot approach for enhancing strain induced pockels effect in the mid ir range
IEEE Photonics Technology Letters, 2021Co-Authors: Irene Olivares, P SanchisAbstract:Strained Silicon was proposed more than a decade ago promising to revolutionize the Silicon photonics field by allowing efficient modulation in this platform. Despite all the efforts, still rather low $\chi {(2)}$ values have been measured in Strained Silicon devices. In addition, the way of applying strain has not barely changed since the concept was proposed, usually consisting on a Silicon waveguide covered by a stressor material such as Silicon nitride. In this letter, a SiGe slot approach is explored as a different route to enhance the strain induced Pockels effect in the mid-IR range. Such approach would allow effective index change values which are near to 10−4 and improve the values expected for the most common Silicon - Silicon nitride structure by more than three orders of magnitude.
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enhanced pockels effect in Strained Silicon by means of a sige si sige slot structure
IEEE Photonics Conference, 2020Co-Authors: Irene Olivares, P SanchisAbstract:A slot waveguide structure made of a SiGe/Si/SiGe heterojunction is proposed to enhance Pockels effect in Strained Silicon. The strain is applied via lattice mismatch between layers, while the slot configuration optimizes the overlap between the optical and electric field inside the Strained Silicon.
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enhancing pockels effect in Strained Silicon waveguides
Optics Express, 2019Co-Authors: Irene Olivares, Jorge Parra, A Brimont, P SanchisAbstract:The magnitude and origin of the electro-optic measurements in Strained Silicon devices has been lately the object of a great controversy. Furthermore, recent works underline the importance of the masking effect of free carriers in Strained waveguides and the low interaction between the mode and the highly Strained areas. In the present work, the use of a p-i-n junction and an asymmetric cladding is proposed to eliminate the unwanted carrier influence and improve the electro-optical modulation response. The proposed configuration enhances the effective refractive index due to the strain-induced Pockels effect in more than two orders of magnitude with respect to the usual configuration.
Laurent Vivien - One of the best experts on this subject based on the ideXlab platform.
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Strained Silicon photonics for Pockels effect based modulation
2017Co-Authors: Mathias Berciano, Pedro Damas, Guillaume Marcaud, Xavier Le Roux, Paul Crozat, Carlos Alonso Ramos, Daniel Benedikovic, Delphine Marris-morini, Eric Cassan, Laurent VivienAbstract:We present on experimental results of straininduced Pockels effect in Silicon based on Mach-Zehnder interferometer modulators. We theoretically studied both Pockels effect and carrier parasitic effect in Silicon under an electric field. We demonstrated high speed Pockels-based optical modulation up to 25 GHz.
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pockels effect in Strained Silicon photonics conference presentation
Proceedings of SPIE, 2017Co-Authors: Laurent Vivien, Mathias Berciano, Pedro Damas, Guillaume Marcaud, Paul Crozat, Daniel Benedikovic, Xavier Le Roux, Carlos Alonsoramos, Delphine Marrismorini, Eric CassanAbstract:Silicon photonics has generated a strong interest in recent years, mainly for optical communications and optical interconnects in CMOS circuits. The main motivations for Silicon photonics are the reduction of photonic system costs and the increase of the number of functionalities on the same integrated chip by combining photonics and electronics, along with a strong reduction of power consumption. However, one of the constraints of Silicon as an active photonic material is its vanishing second order optical susceptibility, the so called χ(2) , due to the centrosymmety of the Silicon crystal. To overcome this limitation, strain has been used as a way to deform the crystal and destroy the centrosymmetry which inhibits χ(2). The paper presents the recent advances in the development of second-order nonlinearities including discussions from fundamental origin of Pockels effect in Silicon until its implementation in a real device. Carrier effects induced by an electric field leading to an electro-optics behavior will also be discussed.
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Pockels Effect in Strained Silicon Waveguides
2017Co-Authors: Mathias Berciano, Pedro Damas, Guillaume Marcaud, Xavier Le Roux, Paul Crozat, Daniel Benedikovic, Delphine Marris-morini, Eric Cassan, Carlos Alonso Ramos, Laurent VivienAbstract:With the increasing demand of data current chip-scale communication systems based on metallic interconnects suffer from rate limitations and power consumptions. In this context, Silicon Photonics has emerged as an alternative solution replacing the classical copper interconnects by Silicon waveguides while taking advantage of the well-established CMOS foundries techniques to reduce fabrication costs. Silicon is now considered as an excellent candidate for the development of integrated optical functionalities. Among all photonic devices required for an optical link, optical modulator is one of the main building blocks. One of the main challenges of Silicon Photonics is the reduction of both power consumption and swing voltage of optical Silicon modulators while increasing the data transfer rate speed. However Silicon is a centrosymmetric crystal, vanishing the second order nonlinear effect i.e. Pockels effect which is intrinsically high speed. Nevertheless it has been showed [1] that mechanical stresses, provided by depositing a Strained overlayer, can break the crystal symmetry and eventually unlock Pockels effect in Silicon. Since then several studies have been performed [2-4] in order to improve the later. But a recent investigation [5] demonstrated that carrier effects have a drastic influence on the measured electro-optic effect. Indeed both plasma dispersion effect and Pockels effect act together under an electric field in Strained Silicon which have led to an overestimation of the second order nonlinear susceptibility. One way to separate these effects consists in the increasing of the modulation speed [6] in order to minimize the impact of free carriers. In this work, we have studied the effect of the stress layer in the modulation characteristics based on Mach-Zehnder interferometers (Fig. 1) in the microwave range. DC and high speed characteristics (Fig. 2) will be presented and discussed.
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Bond orbital description of the strain-induced second-order optical susceptibility in Silicon
Physical Review B: Condensed Matter and Materials Physics, 2016Co-Authors: Pedro Damas, Delphine Marris-morini, Eric Cassan, Laurent VivienAbstract:We develop a theoretical model, relying on the well established sp3 bond-orbital theory, to describe the strain-induced χ (2) in tetrahedrally coordinated centrosymmetric covalent crystals, like Silicon. With this approach we are able to describe every component of the χ (2) tensor in terms of a linear combination of strain gradients and only two parameters α and β which can be theoretically estimated. The resulting formula can be applied to the simulation of the strain distribution of a practical Strained Silicon device, providing an extraordinary tool for optimization of its optical nonlinear effects. The application of the first order theory to the photoelastic effect in C, Si, and Ge showed very good phenomenological and numerical agreement, up to 3% in Si. The model was then used to the second-order nonlinear susceptibility, and we were able not only to confirm the main valid claims known about χ (2) in Strained Silicon, but also estimate the order of magnitude of the χ (2) generated in that device.
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wavelength dependence of pockels effect in Strained Silicon waveguides
Optics Express, 2014Co-Authors: Pedro Damas, Eric Cassan, Xavier Le Roux, Delphine Marrismorini, David Le Bourdais, Nicolas Izard, Thomas Maroutian, Philippe Lecoeur, Laurent VivienAbstract:We investigate the influence of the wavelength, within the 1.3μm–1.63μm range, on the second-order optical nonlinearity in Silicon waveguides Strained by a Silicon nitride (Si3N4) overlayer. The effective second-order optical susceptibility χxxy(2)¯ evolutions have been determined for 3 different waveguide widths 385 nm, 435 nm and 465 nm and it showed higher values for longer wavelengths and narrower waveguides. For wWG = 385 nm and λ = 1630 nm, we demonstrated χxxy(2)¯ as high as 336 ± 30 pm/V. An explanation based on the strain distribution within the waveguide and its overlap with optical mode is then given to justify the obtained results.
Judy L Hoyt - One of the best experts on this subject based on the ideXlab platform.
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design of tunneling field effect transistors using Strained Silicon Strained germanium type ii staggered heterojunctions
IEEE Electron Device Letters, 2008Co-Authors: Osama M Nayfeh, Judy L Hoyt, C N Chleirigh, John Hennessy, L Gomez, D A AntoniadisAbstract:Heterojunction tunneling field-effect transistors (HTFETs) that use Strained-Silicon/Strained-germanium type-II staggered band alignment for band-to-band tunneling (BBT) injection are simulated using a nonlocal quantum tunneling model. The tunneling model is first compared to measurements of gate- controlled BBT in previously fabricated Strained SiGe diodes and is shown to produce good agreement with the measurements. The simulation of the gated diode structure is then extended to study HTFETs with an effective energy barrier of 0.25 eV at the Strained-Si/Strained-Ge heterointerface. As the band alignment, particularly the valence band offset, is critical to modeling HTFET operation, analysis of measured characteristics of MOS capacitors fabricated in Strained-Si/Strained-Ge/relaxed Si0.5Ge0.5 hetero- junctions is used to extract a valence band offset of 0.64 eV at the Strained-Si/Strained-Ge heterointerface. Simulations are used to compare HTFETs to MOSFETs with similar technology parameters. The simulations show that HTFETs have potential for low-operating-voltage (Vdd < 0.5 V) application and exhibit steep subthreshold swing over many decades while maintaining high ON-state currents.
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measurement of enhanced gate controlled band to band tunneling in highly Strained Silicon germanium diodes
IEEE Electron Device Letters, 2008Co-Authors: Osama M Nayfeh, Judy L Hoyt, C N Chleirigh, D A AntoniadisAbstract:Strained Silicon-germanium (Si0.6Ge0.4) gated diodes have been fabricated and analyzed. The devices exhibit significantly enhanced gate-controlled tunneling current over that of coprocessed Silicon control devices. The current characteristics are insensitive to measurement temperature in the 80 K to 300 K range. Independently extracted valence band offset at the Strained Si0.6Ge0.4/Si interface is 0.4 eV, yielding a Si0.6Ge0.4 bandgap of 0.7 eV, which is much reduced compared to that of Si. The results are consistent with device operation based on quantum-mechanical band-to-band (BTB) tunneling rather than on thermal generation. Moreover, simulation of the Strained Si0.6Ge0.4 device using a quantum-mechanical BTB tunneling model is in good agreement with the measurements.
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strain relaxation in patterned Strained Silicon directly on insulator structures
Applied Physics Letters, 2005Co-Authors: R Z Lei, D A Antoniadis, Judy L Hoyt, W Tsai, Ingvar Aberg, T B Oreilly, Henry I Smith, Albert J Paul, M L Green, R HullAbstract:Strain relaxation is studied in Strained Silicon directly on insulator (SSDOI) substrates patterned with nanoscale features. Using interference lithography, biaxially Strained SSDOI substrates with 30nm thick Strained Si on insulator films were patterned into grating structures with 90nm wide stripes, and arrays of 80nm×170nm pillars. The strain profiles of these patterned structures were examined by ultraviolet Raman spectroscopy. Raman analysis of the SSDOI gratings indicates strain relaxation in the 90nm wide stripes, compared to the strain measured in unpatterned portions of the SSDOI wafer. Three-dimensional finite-element modeling of the stress distributions in the grading structures predicts that 95% of the strain is maintained in the direction along the length of the stripes. These simulations are used to decouple the strain components along the width and length of the SSDOI grating structure, inferred from Raman measurements. The results are consistent with substantial stress relaxation across th...
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effect of rapid thermal annealing on strain in ultrathin Strained Silicon on insulator layers
Applied Physics Letters, 2003Co-Authors: T S Drake, D A Antoniadis, Eugene A Fitzgerald, Arthur J Pitera, R Hull, Ni C Chleirigh, Minjoo L Lee, Dalaver H Anjum, N Klymko, Judy L HoytAbstract:The fabrication of ultrathin Strained Silicon directly on insulator is demonstrated and the thermal stability of these films is investigated. Ultrathin (∼13 nm) Strained Silicon on insulator layers were fabricated by epitaxial growth of Strained Silicon on relaxed SiGe, wafer bonding, and an etch-back technique employing two etch-stop layers for improved across wafer thickness uniformity. Using 325 nm Raman spectroscopy, no strain relaxation is observed following rapid thermal annealing of these layers to temperatures as high as 950 °C. The thermal stability of these films is promising for the future fabrication of enhanced performance Strained Si ultrathin body and double-gate metal-oxide-semiconductor field-effect transistors.
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influence of high channel doping on the inversion layer electron mobility in Strained Silicon n mosfets
IEEE Electron Device Letters, 2003Co-Authors: Hasan M Nayfeh, Judy L Hoyt, Eugene A Fitzgerald, C W Leitz, Arthur J Pitera, D A AntoniadisAbstract:In this letter, we investigate the dependence of electron inversion layer mobility on high-channel doping required for sub-50-nm MOSFETs in Strained Silicon (Si), and we compare it to co-processed unStrained Si. For high vertical effective electric field E/sub eff/, the electron mobility in Strained Si displays universal behavior and shows enhancement of 1.5-1.7/spl times/ compared to unStrained Si. For low E/sub eff/, the mobility for Strained Si devices decreases toward the unStrained Si data due to Coulomb scattering by channel dopants.
L Pavesi - One of the best experts on this subject based on the ideXlab platform.
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homodyne detection of free carrier induced electro optic modulation in Strained Silicon resonators
Journal of Lightwave Technology, 2016Co-Authors: Massimo Borghi, Mattia Mancinelli, Martino Bernard, Mher Ghulinyan, Georg Pucker, L PavesiAbstract:In the last few years, Strained Silicon has been proposed as a potential electro-optic material, paving the way to the realization of ultrafast modulators which are compatible with the CMOS fabrication technology. The linear Pockels effect has been used for measuring the magnitude of the induced $\chi ^{(2)}$ components, with values reaching hundreds of $\text{pm/V}$ . Recently, it has been shown that these values could have been overestimated due to the contribution of free carriers to the electro-optic modulation. In this work, this hypothesis is validated by a series of experimental observations, which are performed on Strained Silicon racetrack resonators. These are fabricated with different waveguide widths and orientations. We use a low frequency (KHz) homodyne detection technique to monitor the electro-optic response of the devices. The results indicate that the modulation strength is not dependent on the waveguide geometry or direction. A lot of anomalies are encountered in the device response, which are not compatible with a modulation mechanism of $\chi ^{(2)}$ origin. To this purporse, a theory based on the nonlinear injection of free carriers inside the waveguide is presented. This is able to account for all the observed anomalies.
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high frequency electro optic measurement of Strained Silicon racetrack resonators
Proceedings of SPIE, 2016Co-Authors: Massimo Borghi, Florian Merget, Jeremy Witzens, Mattia Mancinelli, Martino Bernard, Mher Ghulinyan, Georg Pucker, L PavesiAbstract:In this paper, we report on time resolved electro-optic measurements in Strained Silicon resonators. Strain is induced by applying a mechanical deformation to the device. It is demonstrated that the linear electro-optic effect vanishes when the applied voltage modulation varies much faster than the free carrier lifetime, and that this occurs independently on the level of the applied stress. This demonstrates that, at frequencies which lie below the free carrier recombination rate, the electro-optic modulation is caused by plasma carrier dispersion. After normalizing out free carrier effects, it is found an upper limit of (8 ± 3) pm/V to the value of the strain induced χ (2) eff, zzz tensor component. This is an order of magnitude lower than the previously reported values for static electro-optic measurements.
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high frequency electro optic measurement of Strained Silicon racetrack resonators
Optics Letters, 2015Co-Authors: Massimo Borghi, Florian Merget, Jeremy Witzens, Mattia Mancinelli, Martino Bernard, Mher Ghulinyan, Georg Pucker, L PavesiAbstract:The observation of the electro-optic effect in Strained Silicon waveguides has been considered a direct manifestation of an induced χ(2) nonlinearity in the material. In this work, we perform high-frequency measurements on Strained Silicon racetrack resonators. Strain is controlled by a mechanical deformation of the waveguide. It is shown that any optical modulation vanishes, independent of the applied strain, when the applied voltage varies much faster than the carrier effective lifetime and that the DC modulation is also largely independent of the applied strain. This demonstrates that plasma carrier dispersion is responsible for the observed electro-optic effect. After normalizing out free-carrier effects, our results set an upper limit of (8±3) pm/V to the induced high-speed effective χeff,zzz(2) tensor element at an applied stress of -0.5 GPa. This upper limit is about 1 order of magnitude lower than previously reported values for static electro-optic measurements.
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high frequency electro optic measurement of Strained Silicon racetrack resonators
arXiv: Optics, 2015Co-Authors: Massimo Borghi, Florian Merget, Jeremy Witzens, Mattia Mancinelli, Martino Bernard, Mher Ghulinyan, Georg Pucker, L PavesiAbstract:The observation of the electro-optic effect in Strained Silicon waveguides has been considered as a direct manifestation of an induced $\chi^{(2)}$ non-linearity in the material. In this work, we perform high frequency measurements on Strained Silicon racetrack resonators. Strain is controlled by a mechanical deformation of the waveguide. It is shown that any optical modulation vanishes independently of the applied strain when the applied voltage varies much faster than the carrier effective lifetime, and that the DC modulation is also largely independent of the applied strain. This demonstrates that plasma carrier dispersion is responsible for the observed electro-optic effect. After normalizing out free carrier effects, our results set an upper limit of $8\,pm/V$ to the induced high-speed $\chi^{(2)}_{eff,zzz}$ tensor element at an applied stress of $-0.5\,GPa$. This upper limit is about one order of magnitude lower than the previously reported values for static electro-optic measurements.
