Single-photon emitters (SPEs) are quantum systems that can produce individual photons when excited. These photons can be manipulated in their polarization states to encode quantum bits, which are the quantum-mechanical analogs of classical bits. SPEs are critical to the development of quantum information technology applications, including quantum communication, computing, and sensing. Despite their importance, there are currently no solid-state SPEs that meet the requirements for large-scale applications. Researchers have explored various materials hosts, including quantum dots, carbon nanotubes, and bulk semiconductors, but many challenges remain. For example, producing scalable and integrated SPEs with tunable wavelengths, high clocking rates (brightness), and single-photon purity at room temperature is still an ongoing research goal. In recent years, there has been significant research interest in single-photon emitters (SPEs) in two-dimensional (2D) Van der Waals (VdW) materials. Most research in this area has focused on SPEs in multilayer insulating hexagonal boron nitride (hBN), which can be operated at room temperature, and monolayer tungsten diselenide (WSe2), which is a direct bandgap semiconductor. The SPEs in hBN are derived from defect emission, while those in monolayer WSe2 stem from either defect or strain-bound excitons. Despite this promising research, there are critical challenges that impede the development of these SPEs. For example, hBN is an insulator with a band gap of 6.0 eV, which limits electrical control, and controlling defects is difficult. Additionally, the photo-stability of monolayer WSe2 is vulnerable to environmental fluctuations, such as surface contaminants. Multilayer gallium selenide (GaSe) is another 2D Van der Waals (VdW) SPE host, and the initial experimental observation of GaSe SPEs was reported by Tonndorf. et al. in 2017.2,3 However, GaSe SPEs have received less attention compared to hBN and WSe2 for several reasons. Firstly, early reports2,3 show that GaSe SPEs arising from defects are less brighter than SPEs in WSe24 and hBN.5 Secondly, increasing the laser power for brighter GaSe SPEs would cause the formation of biexcitons, which degrades the single photon purity.2 Since 2017, to the best of our knowledge, there have been no further experimental studies conducted on overcoming those challenges to improve the performances of GaSe SPEs. In this dissertation, I present three research projects focused on addressing the challenges of developing single-photon emitters (SPEs) in multilayer gallium selenide (GaSe). First, I achieved localized bright and stable GaSe SPEs in multilayer GaSe through the manipulation of nanoscale strain. Second, I performed below-diffraction limit hyperspectral imaging of strain-localized GaSe SPEs through cathodoluminescence and demonstrated the wide spectral range tunability, significant enhancement of emission intensities controlled by nanoscale strain, as well as the robust spectral stability of GaSe SPEs. In the last project, I demonstrated a 30%-50% improvement in emission intensities of GaSe, converted non-SPEs to SPEs, and increased operating temperatures from 23 K up to 85K above cryogenic temperature through electrostatic doping. The research works in this dissertation lays a crucial foundation for future fundamental studies and the development of GaSe SPEs and their analogues.

In this work, we study the properties and device applications of MoS2, black phosphorus, MoOx, and NbSe2. We first start with the design, fabrication, and characterization of ultra-high responsivity photodetectors based on mesoscopic multilayer MoS2. The device architecture is comprised of a metal-semiconductor-metal (MSM) photodetector, where Mo was used as the contact metal to suspended MoS2 membranes. The dominant photocurrent mechanism was determined to be the photoconductive effect, while a contribution from the photogating effect was also noted from trap-states that yielded a wide spectral photoresponse from UV-to-IR with an external quantum efficiency (EQE) ~ 104. From time-resolved photocurrent measurements, a fast decay time and response time were obtained with a stream of incoming ON/OFF white light pulses. Another interesting semiconductor 2D material that has attracted special attention due to its small bandgap and ultra-high hole mobility is the black phosphorus. An analysis of the optoelectronic properties and photocurrent generation mechanisms in two-dimensional (2D) multilayer crystallites of black phosphorus (BP) was conducted from 350 K down to cryogenic temperatures using a broad-band white light source. The Mo-BP interface yielded a low Schottky barrier "φ" _"SB" ~ -28.3 meV and a high photoresponsivity R of ~ 2.43 x 105 A/W at a source-drain bias voltage of ~ 0.5 V (300 K, and incident optical power ~ 3.16 μW/cm2). Our report is the first to highlight the empirical use of Mo as a contact metal with BP. From the analysis conducted on the BP devices, the thermally driven photocurrent generation mechanism arising from the photobolometric effect (PBE) dominated the carrier dynamics for T > 181 K since the photocurrent Iph and the bolometric coefficient β undergo a transition in polarity from positive to negative. Our results show the promise of BP to potentially advance thermoelectric and optoelectronic devices stemming from this mono-elemental, direct bandgap 2D van der Waals solid. Another intriguing metallic 2D material is superconducting 2H-NbSe2. Here we present the temperature-dependent Raman spectroscopy and electronic transport on bulk NbSe2, carried out to investigate the scattering mechanisms. We report on the photoresponse of direct probed mesoscopic 2H-NbSe2 as a function of laser energy for lasers at 405 nm, 660 nm, and 1060 nm wavelengths used to irradiate the device, where the modulation from the superconducting-to-normal-state is detected through photomodulation. Additionally, the various oxidation levels of molybdenum oxide have interesting optical and electrical properties as a function of the oxygen vacancy and stoichiometry. The substoichiometric MoOx (2 < x < 3) behaves as a high work function conductor due to its metallic defect band. As a result, one of the potential applications of MoOx is for electrical contacts providing high hole injection or extraction. In this work, we have synthesized MoOx nanosheets via chemical vapor deposition and a four-terminal device was fabricated via e-beam lithography and electronic transport was measured as a function of temperature. Outstanding properties were obtained from our MoOx nanosheets, including a high conductivity of ~ 6,680.3 S cm-1, a superior temperature coefficient of resistance ~ -0.10%, and a high sensitivity based on the bolometric coefficient β of ~ 0.152 mS K-1. In summary, this work pushes the state-of-the-art in enabling 2D van der Waals materials for next-generation high-performance detectors.

In the first study, superconducting 2D NbSe₂ was examined towards its prototypical demonstration as a transition-edge sensor, where photoexcitation caused a thermodynamic phase transition in NbSe₂ from the superconducting state to the normal state. The efficacy of the optical absorption was found to depend on the wavelength of the incoming radiation used, which ranged from the ultra-violet (405 nm), visible (660 nm), to the infrared (1060 nm). In the second case involving WSe₂, the UV-ozone treatment revealed the presence of localized excitonic emission in 1L WSe₂ that was robust and long-lived. Our third material platform dealt with hybrid 0D-2D ensembles based on graphene and WSe₂, specifically graphene–endohedral, WSe₂–fullerene (C₆₀), and WSe₂–Au nanoparticles, and exhibited exceptional performance gains achieved with both types of hybrid structures. Next, we investigated WSe₂ based mixed dimensional hybrids. Temperature T-dependent and wavelength λ-dependent optoelectronic transport measurements showed a shift in the spectral response of 1L WSe₂ towards the SPR peak locations of Au-Sp and Au-BP, fostered through the plexciton interactions. Models for the plexcitonic interactions are proposed that provide a framework for explaining the photoexcited hot charge carrier injection from AuNPs to WSe₂ and its influence on the carrier dynamics in these hybrid systems. Last, we studied interactions of vdWs hybrid structures composed of WSe₂ with 0D buckminsterfullerene (C₆₀) spheres. Our results indicate that the C₆₀-WSe₂ vdWs hybrid heterostructure appears to be an attractive architecture for enabling charge transfer and high performance photodetection capabilities. T-dependent electrical transport measurements after C₆₀ deposition revealed a dominant p-type conduction behavior and a significant ×10³ increase in WSe₂ field-effect mobility, with a maximum field-effect mobility of 281 cm²V⁻¹s⁻¹ achieved at 350 K and room-T mobility of 119.9 cm²V⁻¹s⁻¹ for the C₆₀-WSe₂ hybrid.

The push for electronic devices on smaller and smaller scales has driven research in the direction of transition metal dichalcogenides (TMD) as new ultra-thin semiconducting materials. These ‘two-dimensional' (2D) materials are typically on the order of a few nanometers in thickness with a minimum all the way down to monolayer. These materials have several layer-dependent properties such as a transition to direct band gap at single-layer. In addition, their lack of dangling bonding and remarkable response to electric fields makes them promising candidates for future electronic devices. For the purposes of this work, two 2D TMDs were studied, MoS2 and MoTe2. This dissertation comprises of three sections, which report on exploration of charge lifetimes, investigation environmental stability at elevated temperatures in air, and establishing feasibility of UV laser annealing for large area processing of 2D TMDs, providing a necessary knowledge needed for practical use of these 2D TMDs in optoelectronic and electronic devices. (1) A study investigating the layer-dependence on the lifetime of photo-generated electrons in exfoliated 2D MoTe2 was performed. The photo-generated lifetimes of excited electrons were found to be strongly surface dependent, implying recombination events are dominated by Shockley-Read-Hall effects (SRH). Given this, the measured lifetime was shown to increase with the thickness of exfoliated MoTe¬2; in agreement with SRH recombination. Lifetimes were also measured with an applied potential bias and demonstrated to exhibit a unique voltage dependence. Shockley-Read-Hall recombination effects, driven by surface states were attributed to this result. The applied electric field was also shown to control the surface recombination velocity, which lead to an unexpected rise and fall of measured lifetimes as the potential bias was increased from 0 to 0.5 volts. (2) An investigation into the environmental stability of exfoliated 2D MoTe2 was conducted using a passivation layer of amorphous boron nitride as a capping layer for back-gated MoTe2 field effect transistor (FET) devices. A systematic approach was taken to understand the effects of heat treatment in air on the performance of FET devices. Atmospheric oxygen was shown to negatively affect uncoated MoTe2 devices while BN-covered FETs showed remarkable chemical and electronic characteristic stability. Uncapped MoTe2 FET devices, which were heated in air for one minute, showed a polarity switch from n- to p-type at 150 °C, while BN-MoTe2 devices switched only after 200 °C of heat treatment. Time-dependent experiments at 100 °C showed that uncapped MoTe2 samples exhibited the polarity switch after 15 min of heat treatment while the BN-capped device maintained its n-type conductivity. X-ray photoelectron spectroscopy (XPS) analysis suggests that oxygen incorporation into MoTe2 was the primary doping mechanism for the polarity switch. (3) The feasibility of UV laser annealing as a post-process technique to sinter 2D crystal structures from sputtered amorphous MoS2 was explored. Highly crystalline materials are sought after for their use in electron and opto-electronic devices. Sputtered MoS2 has the advantage of potential for large area deposition and high scalability, however, it requires high temperatures (>350 °C) for their crystalline growth. Which creates difficulty for devices grown on polymer substrates. Low-temperature and room temperature deposition results in amorphous films which is detrimental for electric devices. A one-step lase annealing procedure was developed to provide amorphous to crystalline conversion of nanometer thin MoS2 films. Samples were annealed using an unfocused laser beam from a KrF (248 nm) excimer source. The power density was found to be 1.04 mJ/mm2. Raman analysis of laser annealed MoS2 was shown to exhibit a significant improvement of the 2D MoS2 crystallinity compared to as-deposited films on both SiO2/Si, as well as polydimethylsiloxane (PDMS) substrates. Annealed samples showed improvement of their conductivity on an order of magnitude. A top-gated FET device was fabricated on flexible PDMS substrates using Al2O3 as a gate oxide. Measured field effect mobility of annealed samples showed significant improvement over as-deposited devices.

L’objet de cette thèse est l’étude de la croissance de silicène sur des substrats d’argent,ainsi que l’étude de sa réactivité vis-à-vis de l’oxygène. La croissance a été réalisée sous ultra-vide et contrôlée par spectroscopie d’électrons Auger (AES) et par diffraction d’électrons lents (LEED). Les structures obtenues et leurs réactivités à l’oxygène ont été étudiées par microscopie à champ proche (STM et nc-AFM) et par spectroscopie de photoémission résolue en angle (ARPES). Nous avons étudié la structure interne des nano-rubans de silicène auto-assemblés sur un substrat d’Ag(110). Sur Ag(111) nous obtenons un feuillet de silicène qui présente différentes structures en fonction de la température du substrat. L’étude de la réactivité des rubans et des feuillets a montré que le silicène formé sur substrat d’argent est relativement stable vis-à-vis de l’oxygène ce qui ouvre des perspectives de fonctionnalisation du silicène. La dernière partie de cette thèse concerne la synthèse de feuillets de silicium par voie chimique. Nous avons mis au point une nouvelle méthode prometteuse de synthèse chimique qui nous a permis de synthétiser des feuillets de silicium de structure graphitique. / The objective of this thesis is the study of the growth of silicene on silver substrates as well as its reactivity towards the oxygen. The growth was performed under ultra-high vacuum and controlled by Auger electrons spectroscopy (AES) and low energy electrons diffraction (LEED). The obtained structures and their relativities towards the oxygen were studied by near field microscopy (STM and nc-AFM) and by angle resolved electrons photoemission spectroscopy (ARPES). We have studied the internal structure of the selfassembled silicene nanoribbons on Ag(110) substrate. On Ag(111), we have obtained a silicene sheet presenting different structures versus the temperature of the substrate. The reactivity of silicene nanoribbons and sheets grown on silver show that silicene is relatively stable towards the oxygen which opens a new perspectives of functionalization of the silicene. The last part of this thesis concerns the synthesis of silicone sheets by chemical process. We have develpped a new promising process of chemical synthesis which allowed us to synthesize silicon sheets with graphitic structure.

The fast progress in the exploration of 2D materials such as graphene became possible due to development of fabrication techniques that allowed these materials to be protected from e.g. undesirable doping and gave rise to new functionalities realized within van der Waals heterostructures. Attracted by van der Waals interaction the constituent layers of such heterostructures preserve their exceptional electronic quality and for example in graphene allow for high electron mobility to be achieved. However, the studies of atomically thin layers such as NbSe2 that exhibit metallic behavior have been impeded by their reactivity and hence oxidation during exposure to ambient or oxidizing agents such as solvents. In this thesis, the existing heterostructure assembly technique was improved by the introduction of exfoliation and re-stacking by a fully motorized system placed in an inert atmosphere. This approach allowed us to overcome the problem of environmental degradation and create Hall bars and planar tunnel junctions from atomically thin superconducting NbSe2. Furthermore, this versatile approach allowed us to study the thickness dependence of the normal and superconducting state transport properties of NbSe2, uncovering the reduction of the superconducting energy gap and transition temperature in the thinnest samples. On the other hand, 2D materials being just 1-3 atoms thick represent an ultimate example of a membrane - thin but laterally extended object. Consisting of such atomically thin membranes the van der Waals heterostructures can be used for purposes other than the studies of electronic transport. In this work, ubiquitous bubbles occurring during van der Waals heterostructure assembly are employed as a tool to explore 2D materials' mechanical properties and mutual adhesion. This allowed us to measure Young's modulus of graphene and other 2D materials under 1-2% strain and deduce the internal pressure that can reach up to 1 GPa in sub-nanometer size bubbles.

Investigations performed in order to understand the electronic and optoelectronic properties of field effect transistors based on few layers of 2D Copper Indium Selenide (CuIn7Se11) are reported. In general, field effect transistors (FETs), electric double layer field effect transistors (EDL-FETs), and photodetectors are crucial part of several electronics based applications such as tele-communication, bio-sensing, and opto-electronic industry. After the discovery of graphene, several 2D semiconductor materials like TMDs (MoS2, WS2, and MoSe2 etc.), group III-VI materials (InSe, GaSe, and SnS2 etc.) are being studied rigorously in order to develop them as components in next generation FETs. Traditionally, thin films of ternary system of Copper Indium Selenide have been extensively studied and used in optoelectronics industry as photoactive component in solar cells. Thus, it is expected that atomically thin 2D layered structure of Copper Indium Selenide can have optical properties that could potentially be more advantageous than its thin film counterpart and could find use for developing next generation nano devices with utility in opto/nano electronics. Field effect transistors were fabricated using few-layers of CuIn7Se11 flakes, which were mechanically exfoliated from bulk crystals grown using chemical vapor transport technique. Our FET transport characterization measurements indicate n-type behavior with electron field effect mobility µFE ≈ 36 cm^2 V^-1 s^-1 at room temperature when Silicon dioxide (SiO2) is used as a back gate. We found that in such back gated field effect transistor an on/off ratio of ~ 10^4 and a subthreshold swing ≈ 1 V/dec can be obtained. Our investigations further indicate that Electronic performance of these materials can be increased significantly when gated from top using an ionic liquid electrolyte [1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6)]. We found that electron field effect mobility µFE can be increased from ~ 3 cm^2 V^-1 s^-1 in SiO2 back gated device to ~ 18 cm^2 V^-1 s^-1 in top gated electrolyte devices. Similarly, subthreshold swing can be improved from ~ 30 V/dec to 0.2 V/dec and on/off ratio can be increased from 10^2 to 10^3 by using an electrolyte as a top gate. These FETs were also tested as phototransistors. Our photo-response characterization indicate photo-responsivity ~ 32 A/W with external quantum efficiency exceeding 10^3 % when excited with a 658 nm wavelength laser at room temperature. Our phototransistor also exhibit response times ~ tens of µs with specific detectivity (D*) values reaching ~ 10^12 Jones. The CuIn7Se11 phototransistor properties can be further tuned & enhanced by applying a back gate voltage along with increased source drain bias. For example, photo-responsivity can gain substantial improvement up to ~ 320 A/W upon application of a gate voltage (Vg = 30 V) and/or increased source-drain bias. The photo-responsivity exhibited by these photo detectors are at least an order of magnitude better than commercially available conventional Si based photo detectors coupled with response times that are orders of magnitude better than several other family of layered materials investigated so far. Further photocurrent generation mechanisms, effect of traps is discussed in detail.

This thesis describes studies on two-dimensional electron gases (2DEG) in graphene and related 2D systems. Magnetotransport investigations specifically in graphene and its bilayer system are demonstrated in detail, while the experimental techniques presented in this thesis are widely applicable to a large variety of other 2D materials. Chapter 1 gives an introduction and motivation for the principal topic presented in this thesis, with a general introduction to carbon nano-materials and an overview of the current state of graphene-related research and technological development (RTD). Chapter 2 establishes a basic theoretical framework which is essential for interpreting the results presented in this thesis, starting with the crystal and electronic band structures of graphene and its bilayer, followed by high magnetic fields effects on transport properties in these 2D systems. Chapter 3 details the experimental methods directly related to the presented work. The next three chapters report experimental results of three specific magnetotransport studies. Chapter 4 reports the disorder effects on epitaxial graphene in the vicinity of the Dirac point. Quadratic increases of carrier densities with temperature are found to be due to intrinsic thermal excitation combined with electron-hole puddles induced by charged impurities. It is also shown that the minimum conductivity increases with increasing disorder strength, in good agreement with quantum-mechanical numerical calculations. Chapter 5 reports measurements of the quantum Hall effect in epitaxial graphene showing the widest quantum Hall plateau observed to date extending over 50 T, attributed to a magnetic field dependent charge transfer process from charge reservoirs with exceptionally high densities of states in close proximity to the graphene. Using a realistic framework of broadened Landau levels this process is modelled in excellent agreement with experimental results. In Chapter 6, energy relaxation of hot carriers in graphene bilayer systems is investigated from measurements on Shubnikovde Haas oscillations and weak localisation. The hot-electron energy loss rate follows the predicted T⁴ power-law at carrier temperatures from 1.4 up to about 100 K, due to electron-acoustic phonon interactions. Comparisons are made between graphene monolayer and bilayer systems and a much stronger carrier density dependence of the energy loss rate is found in the bilayer system. This thesis concludes with a summary of the most important findings of the topics that have been discussed. The significance and limitations of the present research are listed. Some suggestions and outlook are given for possible improvements and interesting areas of future research and development.

Le sujet de cette thèse est à l’interface entre l’étude de composés à base de nitrure et des structures émergeantes formées par les matériaux bidimensionnels (2D) d’épaisseur atomique. Ce travail se consacre sur l’hybridation des propriétés électriques et optiques des semi-conducteurs à larges bandes interdites que sont les nitrures et des performances mécaniques, électriques et optiques des matériaux lamellaires, récemment isolé à l’échelle d’un plan atomique, qui sont aujourd’hui considérées avec attention aux regards de futures applications et d’études plus fondamentales. En particulier, une étude des propriétés électroniques, optiques et structurelles d’hétérostructures composées de plusieurs matériaux lamellaires et d’interfaces entre matériaux 2D et 3D a été réalisé par des moyens de microscopie et de spectroscopie tel que la spectroscopie Raman, de photoémission et d’absorption.Ce manuscrit traite dans un premier temps des propriétés structurelles et électroniques du nitrure de bore hexagonal (h-BN), matériau isolant aux propriétés optiques exotiques et essentiel dans la future intégration de ce type de matériaux 2D permettant de mettre en valeur leurs propriétés intrinsèques.En utilisant le graphène comme substrat les problèmes de mesures par photoémission rencontrés pour des matériaux isolant ont pu être surmonté dans le cas du h-BN et une étude des défauts structurels a pu être réalisée. Par conséquent, les premières mesures directes de la structure de bande électronique de plusieurs plans de h-BN sont présentées dans ce manuscrit.Dans un second temps, une approche d’intégration de ces matériaux 2D différente a été étudiée en formant une hétérostructure 2D/3D. L’interface de cette hétérojonction, composée d’un plan de disulfure de molybdène (MoS2) de dopage intrinsèque N associé à 300 nm de nitrure de gallium (GaN) intentionnellement dopé P à l’aide de magnésium, a été caractérisée. Un transfert de charge du GaN vers le MoS2 a pu être identifié suggérant un contrôle des propriétés électroniques de ce type de structure par le choix de matériaux.Ces travaux ont permis de révéler les diagrammes de bandes électroniques complet des structures étudiées a pu être obtenu permettant une meilleur compréhension de ces systèmes émergeants. / This thesis is at the interface between the study of nitride based compounds and the emerging structures formed by atomically thin bi-dimensional (2D) materials. This work consists in the study of the hybridization of the properties of large band gap materials from the nitride family and the mechanical, electronic and optical performances of layered materials, recently isolated at the monolayer level, highly considered due to their possible applications in electronics devices and fundamental research. In particular, a study of electronics and structural properties of stacked layered materials and 2D/3D interfaces have been realised with microscopic and spectroscopic means such as Raman, photoemission and absorption spectroscopy.This work is firstly focused on the structural and electronic properties of hexagonal boron nitride (h-BN), insulating layered material with exotic optical properties, essential in in the purpose of integrating these 2D materials with disclosed performances. Using graphene as an ideal substrate in order to enable the measure of insulating h-BN during photoemission experiments, a study of structural defects has been realized. Consequently, the first direct observation of multilayer h-BN band structure is presented in this manuscript. On the other hand, a different approach consisting on integrating bi-dimensional materials directly on functional bulk materials has been studied. This 2D/3D heterostructure composed of naturally N-doped molybdenum disulphide and intentionally P-doped gallium nitride using magnesium has been characterised. A charge transfer from GaN to MoS2 has been observed suggesting a fine-tuning of the electronic properties of such structure by the choice of materials.In this work present the full band alignment diagrams of the studied structure allowing a better understanding of these emerging systems.

Aujourd'hui se pose une question fondamentale sur le futur de l'électronique actuelle. De plus en plus, des circuits hybrides intégrant de nouvelles fonctionnalités sont fabriqués. On envisage même, à plus long terme, des circuits basés sur une technologie différente de l'approche CMOS utilisée actuellement. Une de ces technologies est la spintronique qui tire profit du spin, degré de liberté supplémentaire de l'électron. Elle a rapidement fait ses preuves par le passé dans le stockage non volatile binaire (disques durs) et s'oriente aujourd'hui vers de nouvelles mémoires magnétiques ultra-performantes et basse consommation les MRAMs (Magnetic Random Access Memories). En parallèle, une nouvelle catégorie de matériaux à fort potentiel a émergé : les matériaux bidimensionnels (2D). Ces matériaux, dont le fer de lance est le graphène (une couche d'un atome d'épaisseur de graphite), offrent de nouvelles propriétés inégalées. Leur combinaison via la fabrication d'hétérostructures et la capacité d'avoir un contrôle de leur épaisseur à l'échelle atomique pourrait devenir un atout majeur en électronique et plus particulièrement en spintronique. L'objectif de cette thèse a été l'étude de l'intégration et la démonstration du potentiel en termes de fonctionnalités et de performances de ces nouveaux matériaux 2D au sein de jonctions tunnel magnétiques (MTJs), le dispositif prototype de la spintronique. Au cours de cette thèse, nous avons poursuivi les travaux initiés au laboratoire sur l'intégration dans des MTJs du graphène obtenu via une méthode de dépôt CVD (dépôt chimique en phase vapeur) directe sur l’électrode ferromagnétique inférieure. Nous avons démontré que les propriétés de filtrage en spin et de membrane protectrice contre l'oxydation de l'électrode ferromagnétique (FM) sous-jacente s'étendaient à une unique couche de graphène. Par ailleurs, nous avons aussi pu étudier et améliorer significativement l'amplitude du filtrage en spin et du signal de magnétorésistance observé via l'optimisation des procédés de croissance et d'intégration et le choix de différentes configurations de matériaux ferromagnétiques (Ni(111), Co...). De forts effets de filtrage de spin ont ainsi pu être observés avec des magnétorésistances allant de -15% à plus de +80%, soit presque trois fois l'état de l'art. En parallèle, nous nous sommes aussi intéressés à un autre matériau 2D, le nitrure de bore hexagonal (h-BN), isolant isomorphe du graphène qui s'apparenterait à une barrière tunnel d'un seul atome d'épaisseur. Afin d’étudier le h-BN dans une MTJ, nous avons décidé d’exploiter à nouveau le principe d’une croissance directe par CVD du matériau 2D sur le matériau FM. Des mesures CT-AFM (Conductive Tip Atomic Force Microscopy) nous ont permis de démontrer les propriétés de barrière tunnel homogène du h-BN ainsi que le contrôle possible de la hauteur de barrière avec le nombre de couches de h-BN. De plus, des mesures électriques et de magnétotransport nous ont permis de confirmer l’intégration réussie de la barrière tunnel h-BN dans notre MTJ. Nous avons pu obtenir les premiers résultats de forte magnétorésistance pour du h-BN avec une amplitude de la magnétorésistance de +50%, plus d'un ordre de grandeur au-dessus de l'état de l'art, révélant le potentiel du h-BN. Nous avons enfin aussi pu démontrer l'importance du couplage entre le h-BN et l'électrode FM offrant un potentiel de contrôle inédit sur les effets de filtrage en spin et allant jusqu'à rendre le h-BN métallique. Lors de cette thèse, nous avons pu montrer que l’intégration du graphène et du h-BN dans des MTJs via la croissance directe par CVD est un procédé privilégié pour tirer pleinement profit de leurs propriétés. Les résultats obtenus de forte magnétorésistance et de filtrage en spin laissent entrevoir le fort potentiel du graphène, du h-BN mais aussi des autres nouveaux matériaux 2D à venir pour les MTJs. Ces études ouvrent une nouvelle voie d’exploration pour les MTJs : les 2D-MTJs. / Nowadays a critical issue is raised concerning the future of current electronics. Increasingly, hybrid circuits with new functionalities are manufactured. A longer term approach is even contemplated with circuits based on a technology different from the one currently used (CMOS technology). One of these envisioned technologies is spintronics, which benefits from the spin properties, the electron additional degree of freedom. Spintronics has quickly proven its worth in the past in the field of non volatile data storing (hard drives) and is today moving towards new fast and ultra-low-power magnetic random access memories the MRAMs. Meanwhile, these last few years, a new category of materials with high potential has emerged : the bidimensional materials (2D). These materials, with graphene (one atomically thick layer of graphite) as the forerunner, provide new unrivaled properties. Their combination in the form of heterostructures and the ability to obtain a control of their thickness at the atomic scale could be a major asset for electronics and more specifically spintronics. The purpose of this thesis has been the study of the integration and the demonstration of the potential in terms of functionalities and performances of these new 2D materials inside the prototypical spintronic device: the magnetic tunnel junction (MTJ). During this thesis, we have pursued the work initiated by the laboratory on the integration of graphene in MTJs with direct CVD deposition method (chemical vapor deposition) on the underlying ferromagnetic electrode. We demonstrated that the spin filtering and protective membrane properties (preventing the oxidation of the underlying ferromagnetic electrode (FM)) observed earlier expand to a graphene monolayer. Furthermore, we have also studied and improved significantly the amplitude of the spin filtering and the magnetoresistance signal observed. This was done thanks to the optimization of the growth process, integration, and choice of the different configurations of ferromagnetic materials in our structures (Ni(111), Co...). High spin filtering effects have been observed as a function of the configurations with magnetoristances ranging from -15% to beyond +80%, which is almost three times the state of the art. Meanwhile, we looked at another 2D material, the hexagonal boron nitride (h-BN), an insulating isomorph of graphene which could be considered as an atomically thin tunnel barrier. In order to study h-BN into a MTJ, we took again advantage of direct CVD growth of the 2D material on a ferromagnet. CT-AFM (Conductive Tip Atomic Force Microscopy) measurements allowed us to demonstrate the homogeneous tunnel barrier properties of h-BN and the possible control of the barrier height with the number of h-BN layers. Simultaneously, electrical and magnetotransport measurement in the complete junction allowed us to confirm the achieved integration of the h-BN tunnel barrier into our MTJ. We have been able to obtain the first results of high magnetoresistance for h-BN with values one order of magnitude beyond the state of the art. A magnetoresistance of +50% has been reached, thanks to the optimization of the growth process revealing the potential of h-BN. We have also been able to show the important role of the coupling between h-BN and the FM electrode offering an unprecedented potential of control on the spin filtering effects, ranging up to making the h-BN metallic. During this thesis, we have been able to demonstrate that the integration of graphene and h-BN in MTJs through direct CVD growth is a promising process in order to fully exploit their properties. The results obtained of high magnetoresistance and spin filtering point to the high potential for MTJs of graphene and h-BN but also to all the new 2D materials to come. These studies pave the way for exploring a new path for MTJs : the 2D-MTJs.