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International audience; For CMOS processing compatibility, hybrid bonding of III-V materials on Silicon should be operated below 300°C, requiring an interfacial layer as thin as possible in order not to hamper the electrical transport through the interface. Both SiO 2 and ZnO interfacial layers have been investigated in the case of n-InP/n-Si hybrid heterostructures. Efficient electrical transport through oxide-mediated bonded InP/Si heterostructures is demonstrated, related to tunneling through the oxide-interfacial layer. These electrically-operated oxide-interfacial-layer heterostructures provide both efficient bonding processing and open the field for full 3D design and operation of optoelectronic devices.

Sub-l, below band-gap 2-dimentional nanostructured coupled waveguides arrays demonstrate robust control and a tailored tuning of the coupling coefficient for compact devices.

We developed a technique that enables replacement of a metallic waveguide cladding with a low-index (n≈1.4) material - CaF

Structured Illumination Microscope allows resolutions of 120 nm or 100 nm when combined with TIRF. Here we present an elegant and simple way of further increasing this resolution to

We developed a technique that enables to replace a metallic waveguide cladding with a low-index (n $\sim$ 1.4) material - CaF2 or BaF2 - that in addition is transparent from the mid-IR up to the visible range: elevated confinement is preserved while introducing an optical entryway through the substrate. Replacing the metallic backplane also allows double-side patterning of the active region. Using this approach, we demonstrate strong light-matter coupling between an intersubband transition (lambda $\sim$ 10 microns) and a dispersive resonator, at 300 K and at 78 K. Finally, we evaluate the potential of this approach as a platform for waveguiding in the mid-IR spectral range, with numerical simulations that reveal losses in the 1-10 cm$^{-1}$ range., just accepted in optics express

International audience; The mechanical properties of materials usually depend on the size of the considered object. Silicon, for instance, undergoes between the macroscopic and nanometer scales, a brittle-to-ductile transition at room temperature. Although essential for the constantly developing Si-based nanotechnologies, the origin of this remarkable behaviour change remains undetermined for several years. The observation of the mechanisms responsible for plastic deformation in nano-objects is indeed highly challenging at the microscopic scale. One needs controlling the deformation while identifying induced individual plastic events at the smallest scale during the first stages of plasticity. This work describes nano-compression experiments on 100 nm-diameter Si nanopillars followed by post-mortem analysis of the deformed specimens through SEM and atomic resolution TEM imaging. The observed plastic deformation disrupts the usual description of low-temperature undissociated-dislocations-mediated plasticity and is comforted by molecular dynamics calculations. These results shed a new light on the transition between ductile and brittle regimes in silicon by introducing the missing link between plasticity and fracture.

Direct bonding of III-V semiconductors on silicon has recently become a promising technology for the fabrication of hybrid photonic integrated circuits (PICs). In such hybrid PICs, active optical functions (amplification, emission) are ensured by the direct-gap III-V semiconductor and passive functions (guiding, switching) by the Si guiding layer. One particularly attractive feature of hybrid III-V/Si platforms is the possibility to densely integrate a variety of advanced optical functions in the guiding layer using sub-100 nm patterns in the silicon. Nano-patterning the silicon surface may, however, weaken the adhesion of the III-V semiconductor to silicon, potentially making the hybrid bonded stack subject to debonding in subsequent processing steps, such as cleaving. In this context, quantitatively assessing the adhesion of the III-V to Si in a patterned area and comparing it against the adhesion in a nearby unpatterned area can provide one with feedback useful for improving the patterning , post-patterning surface preparation, or bonding processes. Ultimately, such measurements can allow one to propose optimal designs for advanced embedded optical functions in hybrid III-V/Si PICs. Instrumented nanoindentation, Atomic Force Microscopy and Scanning Transmission Electron Microscopy have been combined ex situ to study the adhesion of thin InP membranes to bulk (100) silicon substrates but also to sub-100nm patterned (100) silicon substrates. Three distinct regimes are identified in the deformation of the InP/Si stacks during these experiments: the first is plastic flow of InP at low loads; the second is elastic debonding of the InP membrane, far from the indented zone at medium loads; lastly, the local amorphisation of the underlying Si substrate at high loads. The regime of intermediate loads is shown to be particularly useful in the evaluation of the surface bonding energy of InP to Si [1,2]. [1] K. Pantzas, E. Le Bourhis, G. Patriarche, A. Itawi, G. Beaudoin, I. Sagnes and A. Talneau Eur. Phys. J. Appl. Phys. 65 (2014) 20702 [2] K. Pantzas, E. Le Bourhis, G. Patriarche, D. Troadec, G. Beaudoin, A. Itawi, I. Sagnes and A. Talneau Nanotechnology 27 (2016) 115707

InP membranes have been bonded oxide mediated onto a patterned and unpatterned Si substrate. Indentation is shown to allow local testing on patterned areas. Both responses on patterned and unpatterned are compared and placed in reference to oxide free bonded membranes. Delamination of the membrane was observed to depend on the presence of patterns in the Silicon substrate. It occurs when the indenting load reached 55 mN for an oxide mediated bonded unpatterned structure and 42 mN for an oxide mediated bonded patterned one. This is in both cases below the value of 80 mN obtained for an oxide free bonded membrane (unpatterned). Weibull analysis of these events yielded a modulus m of magnitude 6 to 10, indicating that delamination fracture is relatively predictable with a weaker resistance obtained in patterned oxide mediated bonding. Delamination of the membrane is the result of constraint of plastic flow by the InP/Si interface. Membrane rotation is induced and increases with the indentation load, until it is sufficient to initiate and propagate an interfacial crack.

Two experimental implementations of the double-cantilever beam experiment, developed to measure the bonding energy in wafer-bonded semiconductors, are compared for the first time. The comparison is carried out in two material combinations relevant to microelectronics and silicon photonics: Si on an insulator and InP on Si. Although the two implementations differ in the scale of the measured sample area, the measurement conditions, and the step in the fabrication process at which they are applied, they are shown to yield the same values for bonding energy within experimental errors. Both techniques also show the same trend in the evolution of bonding energy when the samples are subjected to annealing.

session poster(C3-P02); National audience

In this work we propose a method for reconstructing the profile of rough surfaces with superresolution from far-field scattering measurements obtained with Tomographic Diffractive Microscopy (TDM). The inversion algorithm used in the reconstruction, where the optimization is performed with TE and TM data simultaneously, does not require any regularization step and accounts for multiple scattering.

In order to be compatible with CMOS processing, hybrid bonding of III-V materials on Silicon should be operated at 300 °C, which requires an interface layer. The thinnest layer could be obtained when surfaces are prepared oxide-free and activated. We have investigated several activation processes of de-oxidized surfaces and measured their activation efficiency by X-ray Photoelectron Spectroscopy. We report here on the high structural and optical quality of a hybrid III-V on Silicon interface obtained by bonding under vacuum at 300 °C de-oxidized surfaces activated by ozone. The resulting oxide interface layer is 1.2-nm thick the thinnest already reported. Structural characterization of this interface shows no defect in both crystalline lattices. Hybrid shallow ridge waveguides supporting an optical mode overlapping such an interface show 5 cm−1 propagation losses comparable to the value measured for monolithic InP-based waveguides or SOI waveguides produced with the same technology, evidencing the high optical quality of the hybrid interface. Such a thin layer is favorable for an accurate control of the optical performances within hybrid devices and offers a large versatility for their design.

International audience; We have developed a reflection tomographic microscope in which the sample is reconstructed from different holograms recorded under various angles and wavelengths of incidence. We present an iterative inversion algorithm based on a rigorous modeling of the wave-sample interaction that processes all the data simultaneously to estimate the sample permittivity distribution. We show that using several wavelengths permits a significant improvement of the reconstruction, especially along the optical axis.

Within Silicon-based waveguide arrays, we demonstrate that sub-λ, below band-gap nanostructured waveguides can provide a robust control and a fine tuning of the coupling coefficient, which is considered for an optical isolator integrated on Silicon.

Within Silicon-based waveguide arrays, we demonstrate that sub-λ, below band-gap, nanostructured waveguides can provide a robust control and a fine tuning of the coupling coefficient.

We report on the mechanical response of semiconductor substructures formed by InP membranes bonded to silicon. The bonded surfaces are of the order of ~ 1 cm2 and were bonded using oxide-free direct wafer bonding. Both the plastic response of the InP membrane and the InP/Si interface strength have been investigated using instrumented nanoindentation.

Physical properties of nano-objects differ from what they are in bulk materials when the size decreases down to the nanometre scale. This behavioural change, named size effect, also applies to mechanical properties and has been evidenced in various materials. For instance, at low temperature, bulk silicon is known to be a brittle material while silicon nano-objects exhibit a ductile behavior. Although mechanical properties of silicon have been intensively studied over the last decades, the origin of this remarkable brittle-to-ductile transition at small scales remains, however, undetermined. In this article, a study of the plastic behaviour of nano-pillars is reported. The main results obtained from the combination of numerical calculations and experimental compression tests followed by atomically-resolved transmission electron microscopy imaging are described. We discuss the possibility for perfect dislocations to dissociate at low temperature and the underrated role of shuffle partial dislocations in plastic deformation of silicon. The formation of unexpected extended defects in the {115} planes with increasing plastic strain, also appears as a key-factor leading to the transition between ductile and brittle regimes at small scales.