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We present an epitaxy-based approach for designing a 3C-SiC Capacitive Micromachined Ultrasonic Transducer (CMUT). The design requires to consider a 3C-SiC/Si/3C-SiC heterostructure on a Si substrate. This implies to address different growth steps of SiC on Si and Si on SiC. We present some specific growth related issued, namely the control of selectively grown Si on a masked SiC(100) and the further regrowth of 3C-SiC on a Si (110) layer. The final release of the SiC membrane, to define a CMUT, is also addressed using a simple thermal treatment allowing to suppress several technological steps.

This paper demonstrates the ability of 3CSiC microcantilevers (μCs) to monitor binary gas mixture without sensitive coating. Here, 3CSiC is chosen in particular, as the newly designed sensor will be placed in a radioactive environment. The change in gas concentration is identified using relative shifts in the cantilever’s mechanical resonance frequency (∆fr). The presented microcantilevers work on electromagnetic actuation and inductive detection. In this paper, the fabrication process, optical characterization results using laser Doppler vibrometry and test results under a gas mixture environment are demonstrated. The presented limit of detection shows the ability of 3CSiCμCs to detect less than 1% of hydrogen in nitrogen, which makes them suitable for the targeted application.

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It is shown that substrate pixelisation before epitaxial growth can significantly impact the emission color of semiconductor heterostructures. The wavelength emission from InxGa1−xN/GaN quantum wells can be shifted from blue to yellow simply by reducing the mesa size from 90 × 90 µm2 to 10 × 10 µm2 of the patterned silicon used as the substrate. This color shift is mainly attributed to an increase of the quantum well thickness when the mesa size decreases. The color is also affected, in a lesser extent, by the trench width between the mesas. Cathodoluminescence hyperspectral imaging is used to map the wavelength emission of the InxGa1−xN/GaN quantum wells. Whatever the mesa size is, the wavelength emission is red-shifted at the mesa edges due to a larger quantum well thickness and In composition.

Experimental results presented in this contribution demonstrate that adding HCl to the SiC CVD process is not only an efficient way to suppress the Aluminum memory effect but may also be considered as a powerful tool for fine tuning of intentional Al incorporation in 3C-SiC and 4H-SiC thin films. The approach is easy to implement and seems more reliable than changing TMA bubbling/dilution parameters during the growth. An ad-hoc phenomenological model is proposed to explain the correlation between the HCl supply and Al incorporation.

The present experimental study demonstrates the feasibility of Vanadium doping of 3C-SiC hetero-epitaxial material. Vanadium concentration in 3C-SiC is determined from SIMS measurements. Some of Vanadium incorporation trends as well as the influence of Vanadium doping on 3C-SiC resistivity are observed.

The present work is dedicated to the study of peculiar defects observed in GaN/AlN structures grown on Silicon substrate using the plasma assisted Molecular Beam Epitaxy under metal-rich conditions. Optical microscopy shows that these defects have undefined shape when AlN is grown on Silicon. On the contrary such defects are not observed with AlN films grown under nitrogen-rich plasma assisted or ammonia source Molecular Beam Epitaxy, but triangular shape defects appear in case of GaN regrowth on the latter. As scanning electron microscopy is not able to evidence these defects but only protuberances connected with them, we deduce that they are located in the Silicon substrate. Complementary analysis with atomic force microscopy and energy dispersive X-ray analysis lead us to propose a scenario involving the etching of the Silicon substrate with Ga or Al diffusing through weak points in the nucleation layer.

International audience; Herein, the interest of cubic silicon carbide as a template for the growth of AlGaN/ GaN high electron mobility transistor (HEMT) heterostructures on silicon substrates for high-frequency operation is shown. On the one hand, 0.6-0.8 μm-thick 3C-SiC grown by chemical vapor deposition on intrinsic silicon substrate having initial resistivity superior to 5 kΩ cm enables the metalorganic vapor phase epitaxy of GaN buffer layers with propagation losses below 0.4 dB mm À1 at 40 GHz and 0.5 dB mm À1 at 67 GHz. On the other hand, an HEMT heterostructure is grown on 1.5 μm-thick 3C-SiC on 4 off-axis silicon substrate having an initial resistivity superior to 200 Ω cm that allows to keep a sufficiently resistive epilayer stack limiting the loss up to 0.78 dB mm À1 at 40 GHz. Device process developed on a piece of the 100 mm diameter wafer leads to the demonstration of DC transistor operation with low leakage currents. Compared with direct growth on silicon, these templates enable reduced radio frequency (RF) propagation losses that are very interesting for high-frequency transistors and circuits operation.

First objective of present contribution is to supply a compact description of two thickness-dependent characteristics of state of the art as-grown 3C-SiC/Si templates: structural quality and surface morphology. Second objective is to point out the benefits of surface planarization and indicate the temperature limits of thermal treatment that can be applied to polished 3C-SiC/Si templates without deterioration of planarization results. We believe that this kind of overview, based on our long term experience in fabrication of 3C-SiC/Si templates, may be useful for the scientific community working on future applications of cubic silicon carbide polytype.

We study the cathodoluminescence (CL) and the photoluminescence (PL) properties of In x Ga 1−x N/GaN quantum disks (QDisks) included in nanowires obtained by selective area sublimation from an In x Ga 1−x N/GaN multiple quantum well using an in situ Si x N y nanomasking performed in a molecular beam epitaxy reactor. The NW density can be adjusted as a function of the Si x N y coverage. The mean NW diameter is found almost constant for NW density varying by two orders of magnitude. The light emission from the In x Ga 1−x N/GaN QDisks is blue-shifted compared to the quantum wells. The origin of this shift is discussed in terms of strain and lateral confinement effects in the QDisks. The CL and PL spectra reveal strongly reduced peak linewidths for experiments conducted on a few or single objects isolated by using sub-micrometer apertures in a metallic mask.

In the flourishing fields of quantum technology gallium nitride (GaN) quantum dots (QDs) have great appeal by providing high stability and room-temperature operation. Here, we report on the ion implantation of surface GaN QDs grown in the hexagonal crystal structure. An uncapped sample (S1) and two samples capped by 8 ML (S2) and 16 ML (S3) of AlN are subjected to a 100 keV gallium (S1, S2) and a 210 keV erbium (S3) ion beam. The fluence ranged from 5 × 10 10 cm−2 to 1 × 10 15 cm−2 (S1, S2) and from 5 × 10 10 cm−2 to 5 × 10 13 cm−2 (S3). QD characterization is performed by cathodoluminescence measurements at 77 K and atomic force microscopy and scanning electron microscopy. Strong interdiffusion processes upon ion impact at the interfaces are evidenced leading besides other effects to a quenching of the quantum confined Stark effect. Moreover, a model for the QD morphology based on a fluence-dependent diffusion coefficient is developed.

International audience; Nanopendeo-epitaxy of gallium nitride (GaN) is considered in this study as a way of producing freestanding GaN with reduced strain and threading dislocation density (TDD) for optoelectronic applications. The novelty of this work lies in the use of silicon on insulator (SOI) substrates patterned into nano-pillars down to the buried oxide (BOX). We actually want to benefit from the creeping properties of SiO2 at the growth temperature of GaN for strain relaxation and grain-boundary dislocations reduction. In this paper, we report on the fabrication of 40×40 µm 2 and 300×300 µm 2 freestanding GaN platelets, up to 10 µm-thick, spontaneously separated from the initial pillars. Structural and optical characterizations show that the platelets are crack-free and almost fully relaxed, with a TDD of ∼ 4×10 8 /cm 2. We underline the different benefits of this approach, but most importantly, we believe that it will be the founding-brick for transferable GaN-based devices.

In this work, we report the growth of a 3C-SiC layer oriented along the [111] direction on Si (110)/3C-SiC(001)/Si (001) heterostructure. The growth of the complete layer stack occurs in one deposition run in a Chemical Vapor Deposition (CVD) reactor on on-axis Si (001) substrate. The structural properties of the 3CSiC(111) layer are discussed and the impact of the first 3C-SiC layer on the subsequent growth is highlighted. The 3C-SiC(111) top layer shows two domains rotated by 90o around the growth direction directly linked to the domains rotation in the Si epilayer underneath it. Furthermore, μtwins and stacking faults are present on the inclined (111) planes in the 3C-SiC epilayer.

Exhaustive experimental study of aluminum incorporation in epitaxial 4H-SiC and 3C‑SiC films grown by chemical vapor deposition (CVD) was performed. The influence of polytype and substrate orientation was verified. Role of principal process conditions (growth temperature and pressure, deposition rate, chemical environment) was investigated in details. Finally, the evolution of optical properties of resulting SiC films with Al content was examined.

The aim of this paper is to review the recent developments conducted for the achievement of 3C-SiC‑based heterostructures compatible with MEMS applications. Indeed, the research activities engaged since years permitted to demonstrate that the defect density has an impact towards the Young’s modulus of sub-micron 3C‑SiC epilayers. We also gained knowledge about the stress relaxation mechanisms, targeting to master the stress gradient, as stress is a key parameter to consider MEMS applications.Based on these results, we investigated the elaboration of microstructures using 3C‑SiC/Si/3C‑SiC stacks on silicon substrates. Our first noticeable result was the elaboration of a (110)-oriented 3C‑SiC membrane on a 3C‑SiC pseudo-substrate, using the silicon epilayer as a sacrificial one. But the surface of the 3C‑SiC membrane was facetted and rough, which could hamper its use for the development of new MEMS devices. Then, with further improvements, we succeeded to master the growth of a (111)‑oriented 3C‑SiC epilayer. This feature led to a drastic reduction of the roughness in comparison with the (110) orientation. Actually, using the same experimental protocol than previously, we succeeded to complete a (111)‑oriented 3C‑SiC membrane with a RMS roughness limited to 9nm. Such an optimized structure could be the starting point for the achievement of new MEMS devices operating in harsh environment or for medical applications benefiting of the 3C‑SiC biocompatibility

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International audience; We demonstrate the growth of almost strain-free (10-11) semipolar GaN on silicon-on-insulator (SOI) substrates, with no meltbacketching and with a defect density strongly reduced compared to semipolar templates grown on patterned silicon substrates.This is carried out using SOI substrates with a very thin (∼150 nm) 6° off (001) Si top layer. By resorting to very smallnucleation (111) facets, revealed through chemical etching of the topmost thin Si layer, we are able to diminish significantly theoverall dislocation density. Cathodoluminescence and scanning electron microscopy images at different stages of the growthillustrate how the defect density reduction operates and confirm the complete suppression of meltback etching over the whole2 in. wafer. Low temperature photoluminescence and optical reflectivity indicate that complete strain relaxation is closelyachieved (D0X at 3.473 ± 0.001 eV), compared to semipolar epilayers grown onto “bulk” silicon (D0X at 3.460 eV). Thanks to thisefficient strain relaxation, very thick layers, up to 9 μm, could be obtained crack-free.

We present a high throughput and systematic method for the screening of colour centres in diamond with the aim of searching for and reproducibly creating new optical centres down to the single defect level, potentially of interest for a wide range of diamond-based quantum applications. The screening method presented here should, moreover, help to identify some already indexed defects among hundreds in diamond (Zaitsev 2001 Optical Properties of Diamond (Berlin: Springer)) but also some promising defects of a still unknown nature, such as the recently discovered ST1 centre (Lee et al 2013 Nat. Nanotechnol. 8 487; John et al 2017 New J. Phys. 19 053008). We use ion implantation in a systematic manner to implant several chemical elements. Ion implantation has the advantage of addressing single atoms inside the bulk with defined depth and high lateral resolution, but the disadvantage of producing intrinsic defects. The implanted samples are annealed in vacuum at different temperatures (between 600 degrees C and 1600 degrees C with 200 degrees C steps) and fully characterised at each step in order to follow the evolution of the defects: formation, dissociation, diffusion, re-formation and charge state, at the ensemble level and, if possible, at the single centre level. We review the unavoidable ion implantation defects (such as the GR1 and 3H centres), discuss ion channeling and thermal annealing and estimate the diffusion of the vacancies, nitrogen and hydrogen. We use different characterisation methods best suited for our study (from widefield fluorescence down to subdiffraction optical imaging of single centres) and discuss reproducibility issues due to diamond and defect inhomogeneities. Nitrogen is also implanted for reference, taking advantage of the considerable knowledge on NV centres as a versatile sensor in order to retrieve or deduce the conditions and local environment in which the different implanted chemical elements are embedded. We show here the preliminary promising results of a long-term study and focus on the elements O, Mg, Ca, F and P from which fluorescent centres were found.

Cathodoluminescence reveals structures indicative of gas-assisted epitaxial growth during chondrule melt crystallization., Chondrules, millimeter-sized igneous spherules comprising the major component of most chondritic meteorites, formed during the first 4 million to 5 million years of the evolution of the solar protoplanetary disk and, therefore, can potentially offer important constraints on the conditions in the disk, provided that the processes that led to their formation can be understood. High-resolution cathodoluminescence (CL) survey of chondrules from various chondrite groups revealed changes of CL activator concentrations of magnesium-rich olivines. We show that these overlooked internal zoning structures provide evidence for high-temperature gas-assisted near-equilibrium epitaxial growth of olivines during chondrule formation. We argue that this interaction with the surrounding gas, rather than various cooling histories, defined chondrule composition and texture. Chondrules are thus direct thermochemical sensors of their high-temperature gaseous environment, and high partial pressures of gaseous Mg and SiO are required in their solar protoplanetary disk-forming region to maintain olivine saturation in chondrules. The inferred crystallization of olivines, from stable melts approaching equilibrium with the surrounding gas, provides an explanation for the notable absence of large and systematic isotopic fractionations in chondrules.

The behavior of a high density radical source for the plasma assisted molecular beam epitaxy of GaN and AlGaN compounds is studied and compared with the one of a conventional plasma source. Plasma light emission correlates with the GaN growth rate. Both attest to the better efficiency of the new source for producing active nitrogen species with resulting growth rates well beyond 1 µm/h. The present study shows that GaN films with equivalent structural and optical quality can be grown even with a growth rate enhancement by a factor of 5. The purity of the grown films is investigated as well as point defects. Positron annihilation shows that plasma conditions can be tuned in order to limit the increase of the gallium-vacancy related complexes density by about 2x10 16 cm −3 while reaching growth rates as high as 2.1 µm/h.

We evaluate the influence of the growth parameters on the crystal quality of Si films grown by chemical vapor deposition on 3C-SiC(001)/Si (001) epilayers. It is shown that the pressure plays a major role on the final quality of the films, with two distinct growth regimes. The defects in the films were found to be antiphase boundaries and μ-twins. The influence of the growth parameters as well as the 3CSiC structural properties on these defects are discussed. The impact of a subsequent thermal annealing, under different gas environments, is also investigated and reveals some noticeable differences according to the gas environment used in the annealing process.

Structural investigations of Si quantum dots (QDs) grown by CVD on two different heterostructures: AlN/Si (111) and 3C-SiC/Si (100) are conducted. The Si QDs have been grown using silane as precursor, diluted in hydrogen, at fixed temperature and pressure (830°C - 800mbar). High densities of dots can be obtained (up to 1011 cm-2) with typical heights below 10nm. The kinetic of deposition lets suppose the presence of an initial wetting layer before the dots formation. Different durations are required for nucleating dots on AlN and 3C-SiC. Si QDs on AlN present a luminescence band which can be attributed to quantum confinement.

An exhaustive experimental study of the influence of C/Si ratio on voluntary incorporation of nitrogen (N) and aluminum (Al) in 4H-SiC thin films is presented. The films were grown by chemical vapor deposition (CVD) in a horizontal, hot wall CVD reactor on Si- and C-face substrates, under Si-rich and C-rich conditions. Under some conditions the observed variation of dopant incorporation with C/Si ratio could be clearly attributed to the site competition effects, while in several cases other mechanisms have to be taken into account.

A fraction of a SiNx mono-layer is formed on a GaN layer by exposing the surface to a Si flux. When the sample is heated under vacuum at high temperature (900°C), we observe the sublimation of GaN in the regions uncovered by the thermally resistant SiNx mask. This selective area sublimation (SAS) process can be used for the formation of nanopyramids and nanowires with a diameter down to 4 nm. Also, if InGaN quantum wells are included in the structures before sublimation, InGaN quantum disks with quasi identical sizes in the 3 dimensions of space can be formed using SAS.

International audience; Chemical vapor deposition (CVD) with hydrogen is an interesting technique to grow graphene on silicon carbide (SiC) with excellent electronic properties. However, unanswered questions remain concerning whether the growth mechanism is similar or different to the graphene growth by silicon (Si) sublimation from SiC. In this paper, we emphasize the differences between these two methods based on thermody-namic simulations in an attempt to better understand the different contributors to the graphene formation in both cases. Our calculations prove that our growth technique, i.e. CVD with hydrogen, operates in a completely different thermodynamic system compared to the Si sublimation technique due to the presence of hydrogen. Finally, we complete our simulations with experimental graphene growth attempts which confirm the necessity of an external carbon source to grow graphene under a hydrogen atmosphere in a CVD reactor, unlike the Si sublimation technique.

The silicon carbide cubic polytype (3C-SiC) is perfectly appropriate to fabricate microelectromechanical systems. However, for such applications, the stress can largely influence both the fabrication of 3C‑SiC‑based microsystems and their related mechanical properties. Accordingly, in this study, we investigated the influence of strong aluminum incorporation towards the mechanical properties of 3C-SiC epilayers grown on silicon substrates.

In this study we report the growth of graphene on different silicon carbide substrates by chemical vapor deposition (CVD) in order to understand the influence of the substrate offcut on the graphene layers. For this purpose, graphene was grown on substrates with different offcuts, under hydrogen-argon atmosphere, and analyzed using AFM, LEED and Raman spectroscopy. We discuss the morphology and strain in graphene, and finally the ideal offcut for graphene growth.

We report on the formation of Si dots on SiC surfaces, using chemical vapor deposition technique. Small nanometric objects, with lateral sizes and heights down to 10 and 4 nm respectively, can be obtained, letting expect quantum confinement in the formed dots. The influence, both of the substrate properties and the growth temperature on the dots structure, shape and density, is investigated by means of X ray diffraction, X ray photoemission, scanning electron microscopy, atomic force microscopy and cathodoluminescence. Growing the Si dots on hydrogenated SiC surfaces allows to form (1 1 0) preferentially oriented silicon crystalline objects with densities ranging from 10 9 to some 10 11 cm −2 in dependence on the temperature of growth (850–950 °C). At the opposite, starting the growth on graphitized SiC surfaces significantly modifies the dots properties. In that case, no specific crystalline direction can be evidenced, due to the formation either of Si/SiC dots having a core/shell structure or of fully converted SiC dots.

The aim of this paper is to review the recent developments conducted by our groups for the achievement of 3C-SiC based heterostructures compatible for MEMS applications. It deals with different aspects, from the influence of the defects generated at the 3C-SiC/Si interface on the mechanical properties to the elaboration of new multilayered structures, required for specific applications like, for example, Atomic Force Microscopy.

In this work, we study the influence of 3C–SiC/Si (111) template parameters (thickness, roughness and substrate miscut) on the GaN crystal quality and its strain state. For this, structures with an AlN nucleation layer and 1–4 µm thick GaN layer have been grown by molecular beam epitaxy in order to select the best templates for the growth of thick GaN structures. Similar GaN structures have been grown directly on silicon for comparisons. The influence of the high silicon doping is confirmed on the enhancement of strain relaxation. Despite this limitation, a 5 µm thick crack-free continuous GaN structure (with 1 µm silicon doped) has been successfully grown on the best selected template. Furthermore, the growth by metal–organic chemical vapor deposition of structures with AlN and SiN inter-layers and thick continuous GaN layers on Si (111), 3C–SiC/Si (111) and SoPSiC (silicon on polycrystalline silicon carbide) has been achieved in order to show the relative benefit of each approach in terms of layer quality and strain state.

International audience; The cubic polytype of silicon carbide is an interesting candidate for Micro-Electro-Mechanical-Systems (MEMS) applications due to its tremendous physico-chemical properties. The recent development of multi-stacked Si/SiC heterostructures has demonstrated the possibility to obtain a (110)-oriented 3C–SiC membrane on a 3C–SiC pseudo-substrate, using a silicon layer grown by low pressure chemical vapor deposition as a sacrificial one. However, the (110) orientation of the 3C–SiC membrane led to a facetted and rough surface which could hamper its use for the development of new MEMS devices. Then, in this contribution, an optimized growth process is used to improve the surface quality of the 3C–SiC membrane. The progress relies on the mastering of a (111) orientation for the SiC film, resulting in a smooth surface. Such an optimized structure could be the starting point for the achievement of new MEMS devices in medical or harsh environment applications.

In this contribution, we present a method to form free-standing cubic silicon carbide (3C-SiC) membranes in-situ during the growth stage. To do so, we exploit the presence of voids in the silicon (Si) epilayer underneath the 3C-SiC membrane, in stark contrast to the conventional view of voids as defects. The shape and the size of the 3C-SiC membranes can be controlled by a preceding patterning step of the Si epilayer. Afterwards, by controlling the expansion of voids in Si, the structured sacrificial layer is consumed during the 3C-SiC growth step. Consequently, the membranes are grown and released simultaneously in a single step process. This straightforward technique is expected to markedly simplify the fabrication process of membranes by reducing the fabrication duration and cost. Furthermore, it helps to overcome several technical issues and presents the cornerstone for micro and nano-electromechanical systems applications, profiting from the outstanding properties of cubic silicon carbide.

We have grown graphene films on 6H-SiC(0001) using propane CVD and evidenced the strong impact of the hydrogen/argon mixture used as the carrier gas on the graphene/SiC interface and on the orientation of graphene layers. By studying a set of samples grown with different hydrogen/argon mixture using Raman spectroscopy and grazing incidence X-ray diffraction, we evidence the links between graphene/SiC interface and strain in graphene.

After presenting an exhaustive experimental study of aluminum incorporation in epitaxial 4H-SiC and 3CSiC films grown by chemical vapor deposition (CVD), we focalize once more on what is called site competition effects. We observed that the influence of C/Si ratio on dopant (Al, N) incorporation in SiC was qualitatively different depending on whether the growth experiments were performed in “low temperature” (LT) or “high temperature” (HT) regime. Partial explanation of observed phenomena basing on thermal evolution of carbon coverage of SiC surface is proposed.

The cubic polytype of silicon carbide is a stimulating candidate for Micro-Electro-Mechanical-Systems (MEMS) applications due to its interesting physical and chemical properties. Recently, we demonstrated the possibility to elaborate 3C-SiC membranes on 3C-SiC pseudo-substrates, using a silicon epilayer grown by Low Pressure Chemical Vapor Deposition as a sacrificial layer. Such structures could be the starting point for the elaboration of new MEMS devices. However, the roughness still represents a major concern. Therefore, in this contribution, we investigate the influence of an excimer laser irradiation on the Si epilayer surface prior to the 3C-SiC epilayer growth. We compare these results with the 3C-SiC epilayer grown directly on the as-grown Si epilayer.

Structural and electrical properties of graphene elaborated on 3C-SiC(111)/Si and 3C-SiC(100)/Si templates, using propane-argon gas mixtures under CVD environment, are presented. On 3C-SiC(111), the graphitic phase is clearly attributable to graphene and presents good electrical conductivity at the macroscopic scale. The opposite case is observed on 3C-SiC(100), for which the graphitic phase develops more rapidly but with a high degree of disorientation. The graphitization, which can be coupled with 3C-SiC growth stage, is efficient over the whole surface of 2’’ wafer and allows to elaborate, in a single process, Graphene on Silicon wafers.

14th International Conference on Silicon Carbide and Related Materials (ICSCRM 2011), Cleveland, OH, SEP 11-16, 2011; International audience; We have grown graphene on SiC(0001) using propane-hydrogen CVD. In this work, we present the effects of growth pressure and temperature on structural and electrical properties. Structural characterizations evidence the formation of graphene with in-plane rotational disorder, except for low growth pressure and high growth temperature which lead to the formation of a (6 root 3x6 root 3)-30 degrees interface between graphene and SiC. Electrical properties of samples presenting different graphene/SiC stacking and interfaces are compared and discussed.

We report on the influence of titanium thickness on the structural and electrical properties of annealed Ti/Ni ohmic contacts on highly doped n-type 3C-SiC. Electrical analysis by means of circular transfer length method demonstrate that an interlayer of titanium with thickness in the range of 25-150 nm has no significant influence on specific contact resistance. However, from a structural point of view, the formation of nickel silicides as well as Ti3SiC2 is severely affected by the titanium thickness. Moreover, the Kirkendall effect due to the reaction between Ni and SiC is influenced by the titanium thickness. In fact, Scanning Electron Microscopy analysis demonstrates that the adjunction of titanium affects the distribution of Kirkendall voids in the contact. Current maps determined by conductive Atomic Force Microscopy reveal significant variation of uniformity according to the titanium thickness.

A detailed experimental study of the mean and gradient stress, existing in the as-grown cubic silicon carbide epilayers, is presented in this paper. (100) and (111) oriented epiwafers with considerable film thickness variation have been elaborated using a horizontal low pressure chemical vapor deposition reactor. The mean and gradient stress within the 3C-SiC film were estimated from the static mechanical deformation of micromachined clamped-free beams. For both studied orientations, we observe a stress gradient inversion phenomenon that can be explained in terms of creep occurring in 3C-SiC film.

We have grown graphene on 6H-SiC(0001) and 3C-SiC(111)/Si (111) using propane-hydrogen CVD. This contribution studies the effects of pressure on graphene growth and on its structural properties studied through low energy electron diffraction. We show that varying pressure allows to control the formation of graphene on a (6√3×6√3)-R30° interface reconstruction (low pressure) or graphene with in-plane rotational disorder (high pressure) on both 6H-SiC(0001) and 3C-SiC(111). The effects of the SiC morphology before graphene growth are discussed in order to explain the differences observed between polytypes.

The growth of continuous silicon monocrystalline thin films on 3C-SiC epilayers deposited on silicon substrates is presented in this study. Such heterostructures can be beneficial for the fabrication of Micro Electro Mechanical Systems or electronic applications. The elaboration of these heterostructures was carried out using Low Pressure Chemical Vapor Deposition. X-ray Diffraction, Fourier Transformed Infra-Red spectroscopy and Scanning Electron Microscopy have been used to investigate the structural properties of Si epilayers and their dependence on growth conditions. Monocrystalline Si (110) films are obtained on 3CSiC(100)/Si (100) substrates, only when using growth temperatures close to 850°C. The strong influence of the underlying 3C-SiC film on the final structural properties of Si epilayer is evidenced.

In this paper, we studied the influence of nitrogen implantation dose on both physical and electrical properties in 3C-SiC grown on Si (100) substrate. Scanning Transmission Electron Microscopy characterizations prove that high dose is responsible for amorphization of the implanted layer and the high defect density after annealing. A high V-shape defect density is still found in the implanted layer after an annealing at 1350°C. By lowering the dose, the layer is less damaged and no amorphization is observed. For the different doses, low Specific Contact Resistances are measured using Ti/Ni contacts. The Specific Contact Resistance value decreases from 8x10-6Ω.cm2for the high dose to 3.2x10­6Ω.cm2with decreasing the dose. Furthermore, the dopant activation ratio, evaluated by quantitative SSRM measurements, is improved at the same time from 17% (for the high dose) to 60% (for the low dose). This work demonstrates that high activation ratio can be achieved consecutively to a nitrogen implantation at reasonable implantation fluence.

Graphene growth on SiC using propane-hydrogen CVD has been recently demonstrated. In contrast to the annealing method, in-plane rotational disorder of graphene can be observed on SiC(0001). In this contribution, we study the effects of growth temperature on the interface between graphene and SiC. We show that growth temperature allows to control the formation of graphene with in-plane disorder or graphene on a (6√3×6√3)-R30° interface. Accordingly, grazing incidence X-ray diffraction evidences an effect of growth temperature on in-plane strain. These results are discussed on the basis of the hydrogenation of the SiC surface. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)