Publications by authors named "Ingsong Yu"

The van der Waals epitaxy of wafer-scale GaN on 2D MoS and the integration of GaN/MoS heterostructures were investigated in this report. GaN films have been successfully grown on 2D MoS layers using three different Ga fluxes via a plasma-assisted molecular beam epitaxy (PA-MBE) system. The substrate for the growth was a few-layer 2D MoS deposited on sapphire using chemical vapor deposition (CVD).

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Boron nitride (BN) is a wide-bandgap material for various applications in modern nanotechnologies. In the technology of material science, computational calculations are prerequisites for experimental works, enabling precise property prediction and guidance. First-principles methods such as density functional theory (DFT) are capable of capturing the accurate physical properties of materials.

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The droplet epitaxy of indium gallium nitride quantum dots (InGaN QDs), the formation of In-Ga alloy droplets in ultra-high vacuum and then surface nitridation by plasma treatment, is firstly investigated by using plasma-assisted molecular beam epitaxy. During the droplet epitaxy process, in-situ reflection high energy electron diffraction patterns performs the amorphous In-Ga alloy droplets transform to polycrystalline InGaN QDs, which are also confirmed by the characterizations of transmission electron microscopy and X-ray photoelectron spectroscopy. The substrate temperature, In-Ga droplet deposition time, and duration of nitridation are set as parameters to study the growth mechanism of InGaN QDs on Si.

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In the current study, lignin, an abundant natural polymer, was dissolved in ethylene glycol and acidic HO to form nanoscale lignin. Then, zero-valent iron (ZVI) nanoparticles were synthesized in nanoscale lignin, producing a nZVI/n-lignin composite, via the borohydride reduction method. The use of nZVI/n-lignin for environmental remediation was tested by the removal of methylene blue in aqueous solutions at room temperature.

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Van der Waals epitaxial GaN thin films on c-sapphire substrates with a sp-bonded two-dimensional (2D) MoS buffer layer, prepared by pulse laser deposition, were investigated. Low temperature plasma-assisted molecular beam epitaxy (MBE) was successfully employed for the deposition of uniform and ~5 nm GaN thin films on layered 2D MoS at different substrate temperatures of 500, 600 and 700 °C, respectively. The surface morphology, surface chemical composition, crystal microstructure, and optical properties of the GaN thin films were identified experimentally by using both in situ and ex situ characterizations.

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In this study, flexible and low-cost graphite sheets modified by atmospheric pressure plasma jet are applied to reduced-graphene-oxide/polyaniline supercapacitors. Surface treatment by atmospheric pressure plasma jet can make the hydrophobic surface of graphite into a hydrophilic surface and improve the adhesion of the screen-printed reduced-graphene-oxide/polyaniline on the graphite sheets. After the fabrication of reduced-graphene-oxide/polyaniline supercapacitors with polyvinyl alcohol/HSO gel electrolyte, pseudo-capacitance and electrical double capacitance can be clearly identified by the measurement of cyclic voltammetry.

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Passivation is a key process for the optimization of silicon p-n junctions. Among the different technologies used to passivate the surface and contact interfaces, alumina is widely used. One key parameter is the thickness of the passivation layer that is commonly deposited using atomic layer deposition (ALD) technique.

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This study evaluates DC-pulse nitrogen atmospheric-pressure-plasma-jet processed carbon nanotube (CNT)-reduced graphene oxide (rGO) nanocomposites for gel-electrolyte supercapacitor applications. X-ray photoelectron spectroscopy (XPS) indicates decreased oxygen content (mainly, C-O bonding content) after nitrogen APPJ processing owing to the oxidation and vaporization of ethyl cellulose. Nitrogen APPJ processing introduces nitrogen doping and improves the hydrophilicity of the CNT-rGO nanocomposites.

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In this report, self-organized indium nitride nanodots have been grown on Si (111) by droplet epitaxy method and their density can reach as high as 2.83 × 10(11) cm(-2) for the growth at low temperature of 250 °C. Based on the in situ reflection high-energy electron diffraction, the surface condition, indium droplets, and the formation of InN nanodots are identified during the epitaxy.

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Article Synopsis
  • * Parameters like substrate temperatures, nitridation treatments, and annealing processes significantly influence the quality and density of the GaN nanodots.
  • * Characterization techniques like RHEED, HRTEM, SPEM, and μ-XPS help analyze the surface conditions of the silicon substrate and confirm the formation and composition of the GaN nanodots.
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The surface morphology of Ge0.96Sn0.04/Si(100) heterostructures grown at temperatures from 250 to 450°C by atomic force microscopy (AFM) and scanning tunnel microscopy (STM) ex situ has been studied.

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