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Archive for the ‘Nano Blog’ Category

May 9, 2015 – NIST-led Research Group Creates First Whispering Gallery for Graphene Electrons

Friday, May 15th, 2015

Yue Zhao et al., an international team of scientists at the U.S. Commerce Department’s National Institute of Standards and Technology (NIST), demonstrated nanoscale whispering gallery electron resonance in graphene by using the probe voltage of a scanning tunneling microscope to create a circular pn junction in nanoscale area like a circular wall of mirrors to the electrons and similar to what happens to acoustic wave in the famous whispering gallery of St. Paul’s Cathedral.

“An electron that hits the step head-on can tunnel straight through it,” said NIST researcher Nikolai Zhitenev. “But if electrons hit it at an angle, their waves can be reflected and travel along the sides of the curved walls of the barrier until they began to interfere with one another, creating a nanoscale electronic whispering gallery mode.”

The potential of graphene-based quantum electronic resonators and lenses is believed to be huge.

Read the original press release and article: Center for Nanoscale Science and Technology/ NIST ; *Y. Zhao, J. Wyrick, F. Natterer, J. Rodriguez-Nieva, C. Lewandowski, K. Watanabe, T. Taniguchi, L. Levitov, N. Zhitenev, and J. Stroscio. Creating and probing electron whispering-gallery modes in graphene. Science. 8 May 2015: Vol. 348, no. 6235, pp. 672-675. DOI: 10.1126/science.aaa7469.


credit: Jon Wyrick, CNST/NIST

(Recommended by Ed Perkins, posted by Yonhua Tzeng)


May 8, 2015 – Pathway to the Piezoelectronic Transduction Logic Device

Friday, May 8th, 2015

P. M. Solomon et al. proposed a piezoelectronic transistor (PET) not subject to the voltage limits of field-effect transistors. The PET transduces voltage to stress, activating a facile insulator−metal transition, thereby achieving multi-gigahertz switching speeds, as predicted by modeling, at low power. The team demonstrated a stress-based transduction principle. Read the original article: Nano Lett. 2015, 15, 2391−2395.


(Posted by Yonhua Tzeng. Adapted with permission from Nano Lett. 2015, 15, 2391−2395, DOI: 10.1021/nl5046796 Copyright © 2015 American Chemical Society.)

May 8, 2015 – Flexible CMOS-like Logic Circuits Made of N-type Polymer Sorted Single-Wall Carbon Nanotube

Friday, May 8th, 2015

Huiliang Wang et al. demonstrated flexible CMOS-like logic circuits made of ambipolar single-wall carbon nanotube transistors fabricated without needing for doping processes using high-mobility electron-accepting (n-type) polymer sorted semiconducting SWCNT. Read the original article: Huiliang Wang et al., Adv. Funct. Mater. 2015, 25, 1837–1844. DOI: 10.1002/adfm.201404126  (Posted by Yonhua Tzeng)

n-type polymer doped SWCNT for CMOS-like logic circuit

May 7, 2015 – Majority logic gate for 3D nano-scale magnetic computing

Thursday, May 7th, 2015

Irina Eichwald et al. demonstrated the potential of 3D high integration density digital computing based on physically field interacting nanometer-scaled magnets with a bistable magnetization state, representing the Boolean logic states ‘0’ and ‘1’, arranged in a 3D manner. Read the original article: Irina Eichwald et al 2014 Nanotechnology 25 335202 doi:10.1088/0957-4484/25/33/335202

3D NML computing - Nanotechnology 2014

Schematic of a 3D NML logic system. Logic computing is performed by 3D NAND/NOR gates. Information between functional layers is transmitted by magnetic vias, enabling magnetic signal crossing and computing on a multi-level regime. Electrical in and output sensors enable us to transform magnetic information into the electrical domain and vice versa.

(Posted by Yonhua Tzeng)

May 4, 2015 – Wafer-Level Hysteresis-Free Resonant Carbon Nanotube Transistors

Monday, May 4th, 2015

Wafer-level integration of resonant-body carbon nanotube (CNT) field-effect transistors (FETs) of >1M CNTFETs/cmwith the resonance frequency tunable in situ by both a lateral gate and the back gate has been demonstrated by Ji Cao et al. offering promise in radio frequency signal processing and ultrasensitive sensing.

resonant cnt transistors - ACS Nano 2015

Adapted with permission from ACS Nano, 2015, 9 (3), pp 2836–2842 DOI: 10.1021/nn506817y. Copyright © 2015 American Chemical Society.  (Posted by Yonhua Tzeng)

May 1, 2015 – Fluorinated Epitaxial Graphene Diffusion Barrier on Germanium Enables Ge-MOSFET without Unstable Germanium Oxide

Friday, May 1st, 2015

Zheng et al. demonstrated Ge-MOSFET with negligible C−V hysteresis, extremely low leakage, and superior equivalent oxide thickness by the aid of a fluorinated epitaxial graphene on Ge as an oxygen diffusion barrier to successfully prevent the formation of unstable germanium oxide between the Ge channel and the HfO2 gate oxide.  Read the original article: Xiaohu Zheng et al., Adv. Funct. Mater. 2015, 25, 1805–1813 (Posted by Yonhua Tzeng)

F-Gr on Ge as Diffusion Barrier

a) Schematic diagram showing the implementation of FGra as the diffusion barrier layer between the Ge substrate and HfO 2 dielectric layer in the Ge-based MOS device: (step 1) direct growth of continuous monolayer graphene on Ge; (step 2) FGra synthesized by exposure to SF 6 plasma; (step 3) dielectric deposition on FGra/Ge by atomic layer deposition; (step 4) MOS device completed by standard semiconductor manufacturing processes. b) Cross-sectional high-resolution TEM of the gate stack showing the absence of interfacial oxide formation in the presence of FGra and schematic diagram showing retarded diffusion in the vicinity of high- k /Ge interface.  (Credit Xiaohu Zheng et al., Adv. Funct. Mater. 2015, 25, 1805–1813 with permission)

April 29, 2015 – Subwavelength-scale Photoreduced Graphene Oxides Enable Holographic Images

Wednesday, April 29th, 2015

Xiangping Li et al. demonstrated write-once holograms for wide-angle and full-colour three-dimensional images using subwavelength-scale pulsed femtosecond laser reduction of graphene oxide to enable multilevel optical index modulation and restoration of  vectorial wavefronts of polarization discernible images through the vectorial diffraction of a reconstruction beam. Read the original article: Li et al., Nature Communication  (2015) (Posted by Y. Tzeng)

ncomms7984-f1 - Graphene oxide for hologram - Nature Comm 2015

April 28, 2015 – Squalenoyl adenosine nanoparticles provide neuroprotection after stroke and spinal cord injury

Tuesday, April 28th, 2015

Alice Gaudin et al. used squalenoyl adenosine nanoparticles of the size of ∼120 nm as a neuroprotective drug to deliver therapeutic amounts of drugs by intravenous injection for treating nervous system after stroke and spinal cord injury of mice. Read the original article: Nature Nanotechnology, doi:10.1038/nnano.2014.274  (Posted by Y. Tzeng)

Nanoparticles for treating stroke and spinal injury of mice - Nature Nanotechnology 2014

April 26, 2015 – Low-temperature PECVD of High-mobility Graphene on Copper Foils

Sunday, April 26th, 2015

Boyd et al. of California Institute of Technology demonstrated a microwave plasma-enhanced CVD chemistry in gas mixtures of hydrogen, methane, and nitrogen that grows graphene on copper foils at temperatures lower than 420 °C exhibiting sub-nanometer smoothness, excellent crystalline quality, low strain, few defects and room-temperature electron mobility up to (6.0±1.0) × 10000 cm2 V−1 s−1.  Read the original article: NATURE COMMUNICATIONS doi:10.1038/ncomms7620  ( Posted by Y. Tzeng)

Low-temperature PECVD graphene with very high mobility

April 26, 2015 – Nitrogen-Doped Graphene Oxide Quantum Dots as Photocatalysts for Overall Water-Splitting under Visible Light Illumination

Sunday, April 26th, 2015

Te-Fu Yeh et al. of National Cheng Kung University in Tainan, Taiwan invented nitrogen-doped graphene oxide quantum dots containing p-n type photochemical diodes, which catalyze water-splitting under visible-light irradiation mimicking biological photosynthesis. Read the original article and report: Advanced Materials doi/10.1002/adma.201305299NCKU Research Express


(Upper) Nitrogen-doped graphene oxide quantum dots. (Lower) quantum dot p-n diode  for water splitting. Credit : Te-Fu Yeh et al., Advanced Materials  (Posted by Y. Tzeng)