ORCID Profile
0000-0002-8420-3168
Current Organisation
Nanyang Technological University
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Publisher: Elsevier BV
Date: 12-2019
Publisher: Springer Science and Business Media LLC
Date: 28-07-2015
DOI: 10.1038/NCOMMS8684
Abstract: Gold, silver, platinum and palladium typically crystallize with the face-centred cubic structure. Here we report the high-yield solution synthesis of gold nanoribbons in the 4H hexagonal polytype, a previously unreported metastable phase of gold. These gold nanoribbons undergo a phase transition from the original 4H hexagonal to face-centred cubic structure on ligand exchange under ambient conditions. Using monochromated electron energy-loss spectroscopy, the strong infrared plasmon absorption of single 4H gold nanoribbons is observed. Furthermore, the 4H hexagonal phases of silver, palladium and platinum can be readily stabilized through direct epitaxial growth of these metals on the 4H gold nanoribbon surface. Our findings may open up new strategies for the crystal phase-controlled synthesis of advanced noble metal nanomaterials.
Publisher: AIP Publishing
Date: 07-05-2012
DOI: 10.1063/1.4712565
Abstract: In this work, we present a comprehensive experimental study of charge loss mechanisms in a dual-layer metal nanocrystal (DL-MNC) embedded high-κ/SiO2 gate stack. Kelvin force microscopy characterization reveals that the internal-electric-field assisted tunneling could be a dominant charge loss mechanism in DL devices that mainly depends on the charge distribution in two MNC-layers and inter-layer dielectric (ILD) thickness between the two layers of nanocrystals. Our findings suggest that an optimized DL-MNCs embedded memory cell could be achieved by defining the ILD thickness larger than the average MNC-spacing for enhancement of retention ability in MNC embedded gate stacks. It implies the possibility of reducing MNC spacing in DL structure of scaled memory devices by controlling the thickness of ILD.
Publisher: Springer Science and Business Media LLC
Date: 13-03-2015
DOI: 10.1038/NCOMMS7571
Abstract: Conventionally, the phase transformation of inorganic nanocrystals is realized under extreme conditions (for ex le, high temperature or high pressure). Here we report the complete phase transformation of Au square sheets (AuSSs) from hexagonal close-packed (hcp) to face-centered cubic (fcc) structures at ambient conditions via surface ligand exchange, resulting in the formation of (100)f-oriented fcc AuSSs. Importantly, the phase transformation can also be realized through the coating of a thin metal film (for ex le, Ag) on hcp AuSSs. Depending on the surfactants used during the metal coating process, two transformation pathways are observed, leading to the formation of (100)f-oriented fcc Au@Ag core-shell square sheets and (110)h/(101)f-oriented hcp/fcc mixed Au@Ag nanosheets. Furthermore, monochromated electron energy loss spectroscopy reveals the strong surface plasmon resonance absorption of fcc AuSS and Au@Ag square sheet in the infrared region. Our findings may offer a new route for the crystal-phase and shape-controlled synthesis of inorganic nanocrystals.
Publisher: Elsevier BV
Date: 12-2017
No related grants have been discovered for Chee Lip Gan.