Optomec announced today
that its Aerosol Jet system has been used to fully print Carbon NanoTube (CNT)
based Thin Film Transistors (TFT) with operating frequencies over 5 Gigahertz
(GHz). The work was conducted in collaboration with the University of Massachusetts
and Brewer Science, Inc. The results were recently published in APPLIED PHYSICS
LETTERS (93, 243301 2008) with a paper titled "All [aerosol] jet-printed
carbon nanotube thin-film transistor on a polyimide substrate with an ultrahigh
operating frequency of over 5 GHz."
Printing TFTs on flexible substrates at room temperature offers a cost-effective
way to achieve mass production of large-area electronic circuits without using
special lithography equipment. This is important for many emerging applications
such as flexible displays, RFID tags, electronic paper, and smart skins. The
Aerosol Jet deposition process was used to completely print all four layers
of the Thin Film Transistor including materials with a wide spectrum of viscosities,
making it an ideal solution for this type of multi-layer device.
The paper states that “Printed flexible electronics have been reported
by using various organic semiconducting polymers. However, the carrier mobility
of organic semiconducting polymers is still less than 1.5 cm2 V s, which limits
the device operation speed to only a few kilohertz. Carbon nanotube (CNT), a
material with exceptional aspect ratio and great mechanical flexibility, has
shown great promises as an active carrier transport material in making high-speed
flexible field-effect transistors (FETs). All the elements of the TFT are fabricated
solely by using Aerosol Jet printing technology without involving any photolithography
fabrication steps. An ultrahigh operating frequency of over 5 GHz was demonstrated
with an on-off ratio of over 100.” To read the full text of the paper,
click here (http://www.optomec.com/registration/reg_form?fileid=UML_MEM_Carbon_Nanotube_Paper.pdf).
Dr. Mike Renn (a co-author of the paper) states that “One of the unique
benefits of the Aerosol Jet technology is that it is capable of printing TFT
devices with high drain current, high on-off ratio, and low operation voltage.
Additionally, Aerosol Jet systems have achieved sub-micron layer thicknesses,
and less than 10 micron features sizes and 5 micron registrations.”
Optomec’s Aerosol Jet systems are used in the development of next generation
printable devices such as solar cells, fuel cells, embedded sensors, and more.
Aerosol Jet systems use a patented process that first aerosolizes conductive
and nonconductive inks or pastes and then forms an aerodynamically focused droplet
stream of the material. This Direct Write capability eliminates the need for
screens or stencils required by traditional contact deposition processes while
also enabling much finer feature sizes than is possible with ink jet printing
Optomec is the world-leading provider of additive manufacturing systems for
high-performance applications in the Electronics, Aerospace & Defense, Solar,
and Biomedical markets. These systems utilize Optomec’s proprietary Aerosol
Jet and LENS® powder-metal fabrication technology. The company has a global
customer base of industry-leading manufacturers.