In this work, we report a comparative investigation of InxGa1-xN (SL) and InxGa1-xN/GaN (MQW) structures with an indium content equivalent to x=10%. Both structures are grown on (0001) sapphire substrates using MOCVD and MBE growth techniques. Optical properties are evaluated for samples using PL characteristics. Critical differences between the resulting epitaxy are observed. Microstructures have been assessed in terms of crystalline quality, density of dislocations and surface morphology. We have focused our study towards the fabrication of vertical PIN photodiodes. The technological process has been optimized as a function of the material structure. From the optical and electrical characteristics, this study demonstrates the benefit of InGaN/GaN MQW grown by MOCVD in comparison with MBE for high speed optoelectronic applications.

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.

Instrumented nanoindentation and STEM have been combined ex situ to study the adhesion of 450 nm thick InP membranes to Si 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.

InP membranes have been bonded both oxide free and oxide mediated onto a Si substrate. The mechanical responses of the obtained thin (0.4 µm) membranes could be tested by nanoindentation and compared. Delamination of the membrane was observed to occur when the indenting load reached 55 mN for an oxide mediated bonded structure and 80 mN for an oxide free bonded one. Weibull analysis of these events yielded a modulus m of magnitude 6 to 10, indicating that delamination fracture is relatively predictable with a stronger interface obtained in oxide free approach. 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 induce and propagate an interfacial crack.

High-quality epitaxial silicon thin films have been deposited by plasma-enhanced chemical vapor deposition (PECVD) at 200 °C in a standard radiofrequency (RF) PECVD reactor. We optimized a silicon tetrafluoride (SiF4) plasma to clean the surface of <100> crystalline silicon wafers and without breaking vacuum, an epitaxial silicon film was grown from SiF4, hydrogen (H2), and argon (Ar) gas mixtures. We demonstrate that the H2/SiF4 flow rate ratio is a key parameter to grow high-quality epitaxial silicon films. Moreover, by changing this ratio, we can fine-tune the composition of the interface between the crystalline silicon (c-Si) wafer and the epitaxial film. In this way, at low values of the H2/SiF4 flow rate ratio, an abrupt interface is achieved. On the contrary, by increasing this ratio we can obtain a porous and fragile interface layer, composed of hydrogen-rich microcavities, which allows the transfer of the epitaxial film to foreign substrates.

New fabrication routes for hybrid photonic devices are explored. We report on silicon bonding to III-V semi-conducteurs e.g. Si/InP for emission/amplification function. The materials have been bonded to silicon since it can be nanostructured to obtain optical guides. The bonded surfaces are of the order of ∼ 1 cm2. Special attention has been paid to the surface preparation. The obtained structure has been characterized employing XRD while the mechanical response and interface strength have been investigated employing instrumented nanoindentation.

The use of semiconductor nanowires as new material building blocks for developing original devices is conditioned by the controllability of their growth. An important challenge is to form nanowires which include heterostructures of predictable dimensions. This objective requires a precise knowledge of the growth kinetics which appears much more complex for nanowires than for standard two-dimensional layers. Here, we present a method which provides detailed information on nanowire formation. The method is implemented with InP1-xAsx nanowires grown by Au-catalyzed molecular beam epitaxy. Controlled and periodic modulations of the incident vapor phase are generated. Due to these modulations, the nanowires show small and short oscillations of composition along their growth axis. These oscillations furnish a time scale which is recorded in the nanowire solid phase. The instantaneous growth rate and the total length of individual nanowires at any time of the growth are accessible. Moreover, the distribution of the oscillation lengths contains the nucleation statistics. This statistics is shown to be strongly sub-Poissonian, which indicates that some regulation mechanism operates. The rapid depletion of group V atoms in the catalyst drop which follows the growth of each ML could explain the self-regulation of nucleation events.

The (001) GaAs surfaces have been modified by thin elastically stressed InGaAs-buried layers and tested under Berkovich contact. The elastic–plastic transition determined from the pop-in event observed in the force control mode of the indentation machine appears at slightly lower loads (0.44–0.46 mN) when compared to bare GaAs surface (0.50 mN). Estimations indicate that for both studied sublayers, the stored elastic energy is about 20% of the elastic indentation energy reached at elastic–plastic transition when the sublayer is observed not to relax plastically.

The optical properties of an InAsP/InP quantum well grown on a SrTiO3(001) substrate are analyzed. At 13K, the photoluminescence (PL) yield of the well is comparable to that of a reference well grown on an InP substrate. Increasing the temperature leads to the activation of non-radiative mechanisms for the sample grown on SrTiO3. The main non-radiative channel is related to the thermal excitation of the holes to the first heavy hole excited state, followed by the non-radiative recombination of the carriers on twins and/or domain boundaries, in the immediate vicinity of the well.

Indium phosphide (InP) nanowires (NWs) were grown by molecular beam epitaxy on various substrates including SrTiO3 (001), Si (001) and InP (111) at a growth temperature of 380°C. We used the Vapor Liquid Solid assisted method with Au as a metal catalyst. The composition of the catalyst particles and the crystalline structure of the nanowires were compared using reflection high energy electron diffraction, scanning electron microscopy and high resolution transmission electron microscope. It is found that InP nanowires grown onto InP and SrTiO3 substrates are structurally defects free with a wurtzite structure. On Si (001) substrates, the presence of stacking faults and cubic phase insertion along the growth direction is observed. The effect of the substrate on the composition of catalyst droplets and consequently on the crystalline quality of the nanowires is discussed for the conditions of nucleation and defect formation.

Graphene is generating a considerable interest in materials science and condensed-matter physics. One crucial technological problem, that will govern future applicability of this material, is related to the patterning of graphene while preserving the exceptionally high crystallinity and electronic properties of this material. This article is aiming at demonstrating that a highly focused beam of gallium ions can be applied for sculpting ultra-thin and high quality suspended graphene nano-ribbons (GNRs).

Highly Focused Ion Beams (FIB) are used to produce in one step large quantities of solid state nanopores drilled in thin dielectric films with high reproducibility and well controlled morphologies. We explore both the production of nanopores of various diameters and study their applicability to different biological molecules such as DNA, or folded and unfolded proteins, and then we compare their transport properties. We also report on the translocation of Fibronectin which an original experiment made possible is using the methodology described in this article.

Here we propose to detail an innovative FIB instrumental approach and processing methodologies we have developed for sub-10 nm nanopore fabrication. The main advantage of our method is first to allow direct fabrication of nanopores in relatively large quantities with an excellent reproducibility. Second our approach offers the possibility to further process or functionalize the vicinity of each pore on the same scale keeping the required deep sub-10 nm scale positioning and patterning accuracy. We will summarise the optimisation efforts we have conducted aiming at fabricating thin (10-100 nm thick) and high quality dielectric films to be used as a template for the nanopore fabrication, and at performing efficient and controlled FIB nanoengraving of such a delicate media. Finally, we will describe the method we have developed for integrating these “single nanopore devices” in electrophoresis experiments and our preliminary measurements.

We demonstrate the feasibility of a new approach of Nano Selective Area Growth (Nano-SAG) to precisely localize InAs/InP QDs, by low-pressure Metalorganic Vapour Phase Epitaxy (MOVPE). This approach is based on a partial patterning with a dielectric mask containing nano-openings. The two main advantages of MOVPE are: the important diffusion length of the active species and the inhibition of growth on the dielectric mask. We demonstrate the synthesis of localized nanostructures with high structural properties and the precise control of their dimensions at the nanometer scale. This allows in principle the precise control of the tunability of the emission length.

Decisive advances in the fields of nanosciences and nanotechnologies are intimately related to the development of new instruments and of related writing schemes and methodologies. Therefore we have recently proposed exploitation of the nano-structuring potential of a highly Focused Ion Beam as a tool, to overcome intrinsic limitations of current nano-fabrication techniques and to allow innovative patterning schemes urgently needed in many nanoscience challenges. In this work, we will first detail a very high resolution FIB instrument we have developed specifically to meet these nano-fabrication requirements. Then we will introduce and illustrate some advanced FIB processing schemes. These patterning schemes are (i) Ultra thin membranes as an ideal template for FIB nanoprocessing. (ii) Local defect injection for magnetic thin film direct patterning. (iii) Functionalization of graphite substrates to prepare 2D-organized arrays of clusters. (iv) FIB engineering of the optical properties of microcavities.

InP membranes have been microfabricated and released on top of an InP substrate. The release process comprises membrane photolithography, interlayer sacrificial etching of a InP/InGaAs/InP substructure and drying with CO2 at critical point. The mechanical response of the obtained small (40 µm) and thin (0.4 µm) membranes could be tested by nanoindentation. While keeping their epitaxial orientation through the fabrication process, delamination of the membrane was observed to occur before the indenting load reached 10 mN. Then cracking of the membrane was detected as a pop-in on the loading curves for loads larger than 10 mN.

The paper reports on the synthesis and structural characterization of amorphous silicon oxide nanowires (SiONWs). The nanowires were prepared using the solid-liquid-solid (SLS) technique and display an average mean diameter in the range of 20-150 nm and 15-20 μm in length. Energy dispersive spectrometry (EDS) analysis revealed that the nanowires consist of Si and O elements in a ratio of approximately 1:2. The result was corroborated by the presence of a single peak at around 103 eV in the X-ray photoelectron (XPS) spectrum. As-prepared SiONWs display blue photoluminescence (PL) centered ∼ 400 nm. The blue luminescence is inhomogeneous with an increase in the PL peak intensity by a factor of 1.8 at certain areas of the surface. Next, we have investigated the effect of high-pressure water vapor annealing (HWA) on the PL and found that while the PL became homogeneous, a decrease of its intensity by a factor 2 was observed. The origin of the blue emission could be attributed to defect centers of oxygen deficiency in the wires.

We investigate the magnetic domain pattern in (Ga,Mn)As epilayers with perpendicular magnetic anisotropy. We show that post-growth annealing, besides improving the magnetic and transport properties, also drastically changes the domain pattern. Strong pinning of domain walls along the <110> directions is suppressed and large-size domains are observed.

One of the major challenges during recent years was to achieve the compatibility of III-V semiconductor epitaxy on silicon substrates to combine opto-electronics with high speed circuit technology. However, the growth of high quality epitaxial GaAs on Si is not straightforward due to the intrinsic differences in lattice parameters and thermal expansion coefficients of the two materials. Moreover, antiphase boundaries (APBs) appear that are disadvantageous for the fabrication of light emitting devices. Recently the successful fabrication of high quality germanium layers on exact (001) Si by chemical vapor deposition (CVD) was reported. Due to the germanium seed layer the lattice parameter is matched to the one of GaAs providing for excellent conditions for the subsequent GaAs growth. We have studied the material morphology of GaAs grown on Ge/Si PS using atomic layer epitaxy (ALE) at the interface between Ge and GaAs. We present results on the reduction of APBs and dislocation density on (001) Ge/Si PS when ALE is applied. The ALE allows the reduction of the residual dislocation density in the GaAs layers to 105 cm−2 (one order of magnitude as compared to the dislocation density of the Ge/Si PS). The optical properties are improved (ie. increased photoluminescence intensity). Using ALE, light emitting diodes based on strained InGaAs/GaAs quantum well as well as of In(Ga)As quantum dots on an exactly oriented (001) Ge/Si pseudo-substrate were fabricated and characterized.