Papers by Keyword: CVD

Abstract: Silicon carbide (SiC) is a promising wide-bandgap semiconductor for advanced quantum technologies. Yet, despite progress in bulk and epitaxial growth, a reliable SiC-on-insulator platform remains lacking. Remote epitaxy, mediated by a 2D interlayer, offers a potential pathway to transferable SiC thin films and substrate reuse. In this work, we examine remote epitaxial growth of SiC on epitaxial graphene. We first evaluate the stability of graphene under SiC growth conditions and find that it degrades significantly at the required high temperatures, primarily due to hydrogen and silane etching. With the conditions yielding the highest-quality SiC epitaxial layer; graphene migrates above the SiC rather than remaining at the interface, demonstrating that true remote epitaxy is not achieved. These results highlight the fundamental challenges of SiC remote epitaxy on graphene and point toward critical directions for future exploration.

Abstract: This study investigates the multifaceted relationships between key process parameters such as C/Si ratio, system pressure, temperature, and growth rate and their effects on nitrogen dopant incorporation in homoepitaxial layers on 4H-SiC substrates. We focus on understanding how these growth parameters influence the in situ nitrogen incorporation during chemical vapor deposition (CVD) of epitaxial layers on 150 mm commercially available SiC substrates. Through a carefully designed experimental framework, which explores the interactions between each parameter and the C/Si ratio, we have shed light on a refined approach for epitaxial growth. This approach may not only stabilize the nitrogen dopant concentration across the wafer but possibly also reduces the formation of epitaxial defects.

Abstract: This study aims to synthesize, purify, and modify magnetic carbon nanofibers (Mag-CNF) into hydrophilic carbon material. The synthesis method was carried out by chemical vapor deposition (CVD) using the catalyst from Incolloy at 800°C with argon, nitrogen, hydrogen, and acetylene gases. The purification of Mag-CNF was then conducted by dissolving Mag-CNF with toluene and ethanol, followed by vacuum annealing. The hydrophilization of Mag-CNF was further performed by adding amine groups via reacting Mag-CNF with ethylene diamine, NaNO₂, and H₂SO₄. The successfully prepared Mag-CNF has characteristics of tubular tube bundles consisting of carbon nanofibers with an average diameter of 100-120 nm. The X-ray diffraction (XRD) profile shows the characteristics of carbon, iron, iron oxide, and iron carbide. The Raman spectra show the existence of D, G, and G' bands corresponding to the characteristics of carbon nanomaterials. The magnetic property characterization using a vibration sample magnetometer (VSM) shows the synthesized product as ferrimagnetic materials. The modification results show the addition of hydrophilic groups to Mag-CNF, such as O–H and N–H groups, as analyzed in Fourier Transform Infrared (FTIR) spectra. The successful hydrophilization was also visually confirmed using a dispersion test in water, showing that Mag-CNF has better dispersion after surface modification.

Abstract: The chemical vapor deposition (CVD) growth of boron carbide (B_xC) layers on 4H-SiC, 4°off substrates was studied. Depending on the polarity of the substrate, different results were obtained. On Si face, the direct CVD growth at 1600°C under a mixture of BCl₃+C₃H₈ systematically led to polycrystalline B_xC films, whatever the C/B ratio in the gas phase. On the C face, heteroepitaxial growth was obtained for C/B ratios = 12 or higher with a step bunched morphology. If a boridation step (10 min at 1200°C under BCl₃ flow) was used before the CVD growth, then heteroepitaxy was successful on both substrate polarities. To explain these results, a mechanism is proposed which involves the nature of the chemical bonds at the early stage of nucleation. It is suggested that a full B coverage of the SiC surface should favor the nucleation of the B-rich (0001) plane of B_xC, promoting thus the heteroepitaxial growth along this direction.

Abstract: Silicon Carbide (SiC) Power Devices have emerged as a breakthrough technology for a wide range of applications in the frame of high-power electronics, notably in the 600 to 3,300V. The last decades have shown a continuous and impressive improvement in both 4H-SiC wafer size and quality. Nevertheless, the availability of such wafers remains a challenge for the SiC power industry. In the last three years, Soitec has successfully adapted the Smart Cut™ technology to Silicon Carbide, resulting in the integration of a thin layer of high quality 4H-SiC on an ultra-low resistivity 3C p-SiC handle wafer. The so-called SmartSiC™ offers a drastic yield improvement for the whole industry thanks to the multiple times re-use of the 4H-SiC donor wafer, as well as an improvement of the device’s electrical performance, especially thanks to the ultra-low resistivity polycrystalline silicon carbide (p-SiC). The latter being specially developed to enhance the new SmartSiC™ substrate capabilities. In this paper, we present the work done by Mersen and Soitec to tailor the p-SiC properties, and thus the SmartSiC™ ones including such material.

Abstract: 3C-SiC islands were grown on atomically flat (111) 4H-SiC terraces and characterized by micro-Raman and FTIR. The islands initially have a triangular shape as defined by three {100} planes and over time evolve into hexagonal shaped islands. The triangular shape reveals the domain orientation of the island and is easily observed with an optical microscope. Examining 347 3C-SiC islands on 17 4H-SiC terraces we found that islands grown on the same terrace have the same domain orientation with 99.6% probability. The orientation of 3C-SiC islands grown on adjacent terraces was found to be close to random. This work confirms an orientation selection rule with high probability, suggesting that 3C-SiC can be grown without anti-phase domains or DPBs when grown on a single atomically flat 4H-SiC terrace, even when there are multiple nucleation sites.

Abstract: In this work, the successful heteroepitaxial growth of boron carbide (B_xC) on 4HSiC(0001) 4° off substrate using chemical vapor deposition (CVD) is reported. Towards this end, a two-step procedure was developed, involving the 4H-SiC substrate boridation under BCl₃ precursor at 1200°C, followed by conventional CVD under BCl₃ + C₃H₈ at 1600°C. Such a procedure allowed obtaining reproducibly monocrystalline (0001) oriented films of B_xC with a step flow morphology at a growth rate of 1.9 μm/h. Without the boridation step, the layers are systematically polycrystalline. The study of the epitaxial growth mechanism shows that a monocrystalline B_xC layer is formed after boridation but covered with a B-and Si-containing amorphous layer. Upon heating up to 1600°C, under pure H₂ atmosphere, the amorphous layer was converted into epitaxial B_xC and transient surface SiB_x and Si crystallites. These crystallites disappear upon CVD growth.

Abstract: One of the most often credited materials for opening up new possibilities in the creation of next-generation biosensors is graphene oxide (GO). GO has good water dispersibility, biocompatibility, and high affinity for specific biomolecules due to the coexistence of hydrophobic domains from pristine graphite structure and hydrophilic oxygen containing functional groups, as well as properties of graphene itself that are partly dependent on preparation methods. The high signal output and a strong potential for rapid industrial growth rate, graphene-based materials, such as graphene oxide (GO), are receiving substantial interest in bio sensing applications. Some of graphene's most enticing qualities are its superior conductivity and mechanical capabilities (such as toughness and elasticity), as well as its high reactivity to chemical compounds. The existence of waves on the surface (natural or created) is another property/variable that has immense potential if properly utilized. Single cell detection can be performed by optical biosensors based on graphene. The present state of knowledge about the use of graphene for bio sensing is reviewed in this article. We briefly cover the use of graphene for bio sensing applications in general, with a focus on wearable graphene-based biosensors. The intrinsic graphene ripples and their impact on graphene bio sensing capabilities are extensively examined.

Abstract: The present experimental study demonstrates the feasibility of Vanadium doping of 3CSiC hetero-epitaxial material. Some of Vanadium incorporation trends as well as the influence of Vanadium doping on 3C-SiC resistivity are observed.

Abstract: Tantalum carbide (TaC) coating, produced in an ultrahigh temperature chemical vapor deposition (CVD) process, exhibited high thermal and chemical stabilities, low emissivity, and high purity. Low emissivity of 0.3~0.43 was measured on TaC coating at 1000°C and compared with the one of SiC coating. As revealed in both simulation and experiment, the low emissivity of TaC coatings not only improves temperature uniformity in the SiC PVT process, but also reduces power consumption in both SiC crystal growth and GaN epitaxial deposition. The results provide important guidance to process tuning when switching from a conventional graphite or SiC-coated component to its TaC-coated counterpart.