Publications by authors named "Zewdu Gebeyehu"

The growth of high-quality graphene on flat and rigid templates, such as metal thin films on insulating wafers, is regarded as a key enabler for technologies based on 2D materials. In this work, the growth of decoupled graphene is introduced via non-reducing low-pressure chemical vapor deposition (LPCVD) on crystalline Cu(111) films deposited on sapphire. The resulting film is atomically flat, with no detectable cracks or ripples, and lies atop of a thin CuO layer, as confirmed by microscopy, diffraction, and spectroscopy analyses.

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Article Synopsis
  • Researchers developed highly sensitive Hall sensors using monolayer single-crystal graphene, achieving a carrier mobility over 12000 cm V s and low residual carrier density.
  • The sensors demonstrated a Hall sensitivity greater than 5000 V A T, a level typically reached only with more complex methods involving encapsulated graphene.
  • They also introduced a simple polymeric encapsulation technique, which stabilizes the sensor performance in ambient conditions and reduces degradation over extended periods, enhancing the potential for graphene-based Hall sensors in practical applications.
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Copper (Cu) is the electrical conductor of choice in many categories of electrical wiring, with household and building installation being the major market of this metal. This work demonstrates the coating of Cu wires-with diameters relevant for low-voltage (LV) applications-with graphene. The chemical vapor deposition (CVD) coating process is rapid, safe, scalable, and industrially compatible.

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Single-layer molybdenum ditelluride (MoTe) has attracted attention due to the smaller energy difference between the semiconducting (1H) and semimetallic (1T') phases with respect to other two-dimensional transition metal dichalcogenides (TMDs). Understanding the phenomenon of polymorphism between these structural phases is of great fundamental and practical importance. In this paper, we report a 1H to 1T' phase transition occurring during the chemical vapor deposition (CVD) synthesis of single-layer MoTe at 730 °C.

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Graphene grown chemical vapour deposition (CVD) on copper foil has emerged as a high-quality, scalable material, that can be easily integrated on technologically relevant platforms to develop promising applications in the fields of optoelectronics and photonics. Most of these applications require low-contaminated high-mobility graphene (, approaching 10 000 cm V s at room temperature) to reduce device losses and implement compact device design. To date, these mobility values are only obtained when suspending or encapsulating graphene.

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Intercalation of atomic species through epitaxial graphene on silicon carbide began only a few years following its initial report in 2004. The impact of intercalation on the electronic properties of the graphene is well known; however, the intercalant itself can also exhibit intriguing properties not found in nature. This realization has inspired new interest in epitaxial graphene/silicon carbide (EG/SiC) intercalation, where the scope of the technique extends beyond modulation of graphene properties to the creation of new 2D forms of 3D materials.

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A gravimetric method for the quantitative assessment of the products of electrolysis of water is presented. In this approach, the electrolysis cell was directly powered by 9 V batteries. Prior to electrolysis, a known amount of potassium hydrogen phthalate (KHP) was added to the cathode compartment, and an excess amount of KHCO was added to the anode compartment electrolyte.

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Exposing graphene to a hydrogen post-etching process yields dendritic graphene shapes. Here, we demonstrate that similar dendritic structures can be achieved at long growth times without adding hydrogen externally. These shapes are not a result of a surface diffusion controlled growth but of the competing backward reaction (etching), which dominates the growth dynamics at long times due to an rise in the hydrogen partial pressure.

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