July 20, 2011 — Applied Nanotech Holdings, Inc. (OTC BB: APNT) signed a license agreement for its solar ink and paste technology with Sichuan Anxian Yinhe Construction and Chemical Group (YHCC). The license is worth $2 million upfront for APNT, and allows the company access to Asia’s solar manufacturing industry.

The companies have partnered since February, with this being the first license agreement.

Under the terms of the license, Applied Nanotech will receive an upfront payment of $2.0 million and an ongoing royalty of 3% on sales of solar inks and pastes by YHCC. The first $1.5 million of the upfront payment is payable no later than August, 2011. The remaining $500,000 is payable in April 2012, assuming certain technical specifications have been met. The license agreement grants YHCC an exclusive license for Applied Nanotech’s solar ink and paste technology in Asia, excluding Korea and Japan.

YHCC has begun construction on a manufacturing facility to produce solar inks in its technical park in China. Applied Nanotech’s aluminum pastes are the first products that YHCC will begin producing and is expected to be manufacturing and selling these pastes in 2012.

This license agreement gives Applied Nanotech exposure to the fast-growing solar manufacturing market in Asia. 20.5GW of solar photovoltaics were fabbed in 2010, mostly in China and Taiwan.

Applied Nanotech’s solar inks will be the first products introduced in the strategic partnership with YHCC. The parties are continuing discussions related to other collaboration opportunities. YHCC’s agreement represents APNT’s third licensee that will have products in the market and generating royalties in 2012, noted Doug Baker, CEO of Applied Nanotech Holdings Inc.

Applied Nanotech Holdings Inc. is a premier research and commercialization organization focused on solving problems at the molecular level. Applied Nanotech’s website is www.appliednanotech.net.

Located in Sichuan Province, China, YHCC currently operates through 9 separate subsidiaries located in three specialized industrial parks, occupying over 3,000 acres (700 U.S. acres). YHCC’s website is http://www.yhcc.com/en/.

July 18, 2011 — Georgia Institute of Technology (Georgia Tech)’s thermochemical nanolithography (TCNL) is used to fabricate nanometer-scale ferroelectric structures directly on flexible plastic substrates without the conventional aggressive processing temperatures that would destroy these substrate materials.

Photo 1. Suenne Kim, Georgia Tech postdoctoral fellow, holds a sample of flexible polyimide substrate used in the heated AFM TCNL research. Assistant professor Nazanin Bassiri-Gharb and graduate research assistant Yaser Bastani are also featured. Credit: Gary Meek.

TCNL uses a heated atomic force microscope (AFM) tip to produce patterns. The AFM-based litho process could build high-density, low-cost, complex ferroelectric structures, enabling energy harvesting arrays, sensors, and nano-electromechanical systems (NEMS) and micro-electromechanical systems (MEMS).

The piezoelectric materials can be made into precise shapes and deposited accurately on a flexible substrate, said Nazanin Bassiri-Gharb, assistant professor, Georgia Tech School of Mechanical Engineering. The structures were "directly grown with a CMOS-compatible process" at the smallest resolution acheived to-date, Bassiri-Gharb adds, pointing out that lower-temperature processing isn’t the only benefit to the process. Wires were built to 30nm wide; spheres were made with 10nm diameters.

The researchers envision ferroelectric memory applications, depositing spheres at densities exceeding 200 gigabytes per square inch, said Suenne Kim, a postdoctoral fellow in laboratory of Professor Elisa Riedo in Georgia Tech’s School of Physics.

Image 1. The topography (by AFM) of a ferroelectric PbTiO3 (PTO) line array crystallized on a 360nm-thick precursor film on polyimide. Scale bar = 1um. Credit: Suenne Kim.

Piezoelectric materials often require 600°C+ crystallization temperatures, making flexible substrates (i.e., for energy harvesting) incompatible with processing. Chemical etching produces grain sizes as large as the nanoscale features the researchers would like to produce; physical etch damages structures, reducing the piezoelectric materials’ special properties.

The thermochemical nanolithography process, under development at Georgia Tech starting in 2007, uses very localized heating to form structures where the resistively heated AFM tip contacts a precursor material. The sol-gel precursor is applied in standard spin coating, then heated to 250°C to remove organic solvents. The AFM "writes" crystallized material in a computer-controlled pattern.

Image 2. Scanning electron microscope (SEM) image of a large Pb(ZrTi)O3 (PZT) line array crystallized on a 240nm-thick precursor film on a platinized silicon wafer. Credit: Yaser Bastani.

The researchers have used polyimide, glass and silicon substrates, but in principle, any material able to withstand the 250°C precursor heating would be a viable substrate. Structures have been made from PZT and PTO.

The heated AFM tips were provided by William King, a professor in the Department of Mechanical Science and Engineering at the University of Illinois at Urbana-Champaign.

Researchers will now combine AFM tips in to arrays to pattern large areas. They also plan to improve upon the heated AFM tips for longer operation. Both development areas hint at commercialization, as an alternative to photolithography at the nano scale, avoiding cleanroom and vacuum environments.

Researchers also must study "the growth thermodynamics of these ferroelectric materials," adds Bassiri-Gharb. They will examine materials properties at bulk, micron, and nano scale. "We need to understand what really happens to the extrinsic and intrinsic responses of the materials at these small scales."

Photo 2. Georgia Tech researchers display samples of materials on which ferroelectric nanostructures have been fabricated by thermochemical nanolithography. They are (l-r) graduate research assistant Yaser Bastani with silicon, assistant professor Nazanin Bassiri-Gharb with polyimide and postdoctoral fellow Suenne Kim with glass. Credit: Gary Meek.

The research was sponsored by the National Science Foundation and the U.S. Department of Energy.  In addition to the Georgia Tech researchers, the work also involved scientists from the University of Illinois Urbana-Champaign and the University of Nebraska Lincoln.

Results were reported July 15 in the journal Advanced Materials. Access it here: http://onlinelibrary.wiley.com/doi/10.1002/adma.201101991/abstract

In addition to those already mentioned, the research team included Yaser Bastani from the G.W. Woodruff School of Mechanical Engineering at Georgia Tech, Seth Marder and Kenneth Sandhage, both from Georgia Tech’s School of Chemistry and Biochemistry and School of Materials Science and Engineering, and Alexei Gruverman and Haidong Lu from the Department of Physics and Astronomy at the University of Nebraska-Lincoln.

Courtesy of John Toon, [email protected].

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July 15, 2011 — US Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) researchers have used the Lab’s Advanced Light Source (ALS) to determine that graphene is a special kind of semimetal.

"Graphene is not a semiconductor, not an insulator, and not a metal," explained David Siegel, graduate student in Berkeley Lab’s Materials Sciences Division (MSD) and a member of Alessandra Lanzara’s group in the Department of Physics at the University of California at Berkeley.

An ALS beamline 12.0.1 probed a specially prepared sample of graphene with angle-resolved photoemission spectroscopy (ARPES) to observe how undoped graphene behaves near the Dirac point, a feature of graphene’s band structure.

Semiconductors have bandgaps (an energy gap between the electron-filled valence band and the unoccupied conduction band). Graphene’s valence and conduction bands are represented by two Dirac cones with touching points that cross linearly at the Dirac point (see the figure). In undoped graphene, the valence band is completely filled and the conduction band is completely empty.

The ARPES experiment measured a slice through the cones by directly plotting the kinetic energy and angle of electrons that fly out of the graphene sample when they are excited by the ALS x-ray beam. The emitted electrons hit the detector and build a spectrum, a picture of the Dirac cones.

The electron interaction in undoped graphene excludes graphene from being a metal. The sides of the cone (or legs of the X, in an ARPES spectrum) develop a distinct inward curvature, indicating that electronic interactions are occurring at increasingly longer range — up to 790 angstroms apart — and lead to greater electron velocities. These are unusual previously unknown manifestations of renormalization.

To study graphene without the inteference caused by a substrate, Siegel’s team developed "quasi-freestanding" graphene: Driving silicon out of a silicon carbide substrate to build a relatively thick layer of graphite. Adjacent layers of graphene in the thick graphite sample are rotated with respect to one another, so that each layer in the stack behaves like a single isolated layer.

"Undoped graphene really does differ from what we expect for a normal Fermi liquid, and our results are in good agreement with theoretical calculations," reported Siegel. Unscreened, long-range interations among electrons demonstrate this abnormal behavoir.

"Many-body interactions in quasi-freestanding graphene," by David A. Siegel, Cheol-Hwan Park, Choongyu Hwang, Jack Deslippe, Alexei V. Fedorov, Steven G. Louie, and Alessandra Lanzara, appears in Proceedings of the National Academy of Sciences, online at http://www.pnas.org/content/early/2011/06/20/1100242108.abstract

Siegel, Deslippe, Louie, and Lanzara are members of Berkeley Lab’s Materials Sciences Division and the UCB Department of Physics. Park is with UCB’s Department of Physics, Hwang is with the Materials Sciences Division, and Fedorov is with the Advanced Light Source. This work was supported by the National Science Foundation and the U.S. Department of Energy’s Office of Science.

In the figure below, the conventional Dirac cones of graphene are drawn, with straight sides (left) indicating a smooth increase in energy. An ARPES spectrum near the Dirac point of undoped graphene (sketched in red at right) exhibits a distinct inward curvature, indicating electronic interactions occurring at increasingly longer range and leading to greater electron velocities.