Publications by authors named "Hezhi Zhang"

A high aluminum (Al) content -(AlGa)O film was synthesized on c-plane sapphire substrate using the gallium (Ga) diffusion method. The obtained -(AlGa)O film had an average thickness of 750 nm and a surface roughness of 2.10 nm.

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Pre-plastic deformation (PPD) treatments on bulk metallic glasses (BMGs) have previously been shown to be helpful in producing multiple shear bands. In this work, the applicability of the PPD approach on BMGs with different Poisson's ratios was validated based on experimental and simulation observations. It was found that for BMGs with high Poisson's ratios (HBMGs, e.

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A flexible nitride p-n photodiode is demonstrated. The device consists of a composite nanowire/polymer membrane transferred onto a flexible substrate. The active element for light sensing is a vertical array of core/shell p-n junction nanowires containing InGaN/GaN quantum wells grown by MOVPE.

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Epitaxial growth of GaN nanowires on graphene is demonstrated using molecular beam epitaxy without any catalyst or intermediate layer. Growth is highly selective with respect to silica on which the graphene flakes, grown by chemical vapor deposition, are transferred. The nanowires grow vertically along their c-axis and we observe a unique epitaxial relationship with the ⟨21̅1̅0⟩ directions of the wurtzite GaN lattice parallel to the directions of the carbon zigzag chains.

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We report the first demonstration of flexible white phosphor-converted light emitting diodes (LEDs) based on p-n junction core/shell nitride nanowires. GaN nanowires containing seven radial InGaN/GaN quantum wells were grown by metal-organic chemical vapor deposition on a sapphire substrate by a catalyst-free approach. To fabricate the flexible LED, the nanowires are embedded into a phosphor-doped polymer matrix, peeled off from the growth substrate, and contacted using a flexible and transparent silver nanowire mesh.

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We report on the demonstration of substrate-free nanowire/polydimethylsiloxane (PDMS) membrane light-emitting diodes (LEDs). Metal-organic vapour-phase epitaxy (MOVPE)-grown InGaN/GaN core-shell nanowires were encapsulated into PDMS layer. After metal deposition to p-GaN, a thick PDMS cap layer was spin-coated and the membrane was manually peeled from the sapphire substrate, flipped upside down onto a steel holder, and transparent indium tin oxide (ITO) contact to n-GaN was deposited.

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Article Synopsis
  • - The study focused on creating and analyzing core/shell InGaN/GaN nanowire LEDs, demonstrating that single nanowires and arrays have similar light emission characteristics, indicating good uniformity.
  • - Electroluminescence spectra showed different peaks related to blue and green emissions, with techniques used to enhance blue light while minimizing green light effectively.
  • - By altering contact layouts and applying plasma treatments, researchers found ways to control emitted light color in these LEDs, though some modifications led to reduced blue intensity when removing green emission sources.
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We demonstrate large area fully flexible blue LEDs based on core/shell InGaN/GaN nanowires grown by MOCVD. The fabrication relies on polymer encapsulation, nanowire lift-off and contacting using silver nanowire transparent electrodes. The LEDs exhibit rectifying behavior with a light-up voltage around 3 V.

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