Printing nanomaterials brings 3-D electronics
nanotechweb.org/articles/news/6/1/2/1
4 January 2007
A team from the University of Illinois, Urbana-Champaign, US, has come
up with a printing technique that is able to combine layers of
dissimilar semiconductors, such as single-walled carbon nanotubes and
micro- and nanoscale forms of gallium nitride, silicon and gallium
arsenide, on a range of substrates. The method can create ultrathin
multilayer stacks of thin-film transistors, photodiodes, metal oxide
semiconductor field-effect transistors (MOSFETs) and other components.
FET
"We are interested in unusual classes of electronic devices that cannot
be achieved easily with conventional, wafer-based approaches," John
Rogers of the University of Illinois, Urbana-Champaign told
nanotechweb.org. "Examples include mechanically flexible circuits for
paperlike displays, heterogeneously integrated electronics for
communication or imaging devices, and large area electronics for
structural health monitoring. We believe that the electronics necessary
for these sorts of applications can be achieved by combining printing
techniques with semiconductor nanomaterials."
To make the devices, first the team synthesized nanomaterials such as
single-walled carbon nanotubes, and aligned arrays of single-crystal
nanoscale wires and ribbons of gallium nitride, silicon and gallium
arsenide. In the next step, an elastomeric stamp-based printing
technique transferred the nanomaterials to a device substrate.
The method used a stamp of polydimethylsiloxane - laminating this
against the nanomaterial created van der Waals adhesion contacts and
enabled removal of the material from the source substrate. Applying the
resulting "inked" stamp to a device substrate covered with a thin layer
of liquid prepolymer transferred the nanomaterial to the device
substrate. The team then cured the polymer to make the transfer
permanent.
The method suits device substrates such as flexible plastic, glass
plates or semiconductor wafers. What's more, there is no need for
epitaxial growth or wafer bonding.
"In this approach, the integration of the active materials with the
target substrate, which might include low temperature plastic, can occur
in an additive fashion and at room temperature," said Rogers.
Following processing such as adding gate dielectrics, electrodes and
interconnects, the printing process can be repeated to add further
layers of nanomaterial.
"For flexible electronics, these approaches enable much higher device
performance than can be achieved with organic semiconductors," said
Rogers. "For heterogeneous and 3D electronics, the techniques can avoid
some of the challenges and limitations associated with wafer bonding and
epitaxial growth. The resulting systems that we demonstrate - i.e. high
performance, heterogeneous electronics on plastic, in 2D or 3D layouts -
are, to the best of our knowledge, unique."
The researchers say they hope to investigate applications that are not
well addressed with established wafer- or glass-based electronics
technologies, such as high-speed communication and imaging devices that
combine compound semiconductors with silicon in unusual ways. "Flexible
displays, and large area electronics for structural and personal health
monitors are other examples," said Rogers. "In a current project, we are
working on electronic eye type imagers. Further out into the future, we
hope that these flexible electronic devices could be used in certain
types of medical implants."
Now the team plans to investigate scale-up and integration of the
technique into realistic prototype applications. "We are, therefore,
focused on activities such as the development of a printer system that
can build backplanes for displays, as a first step to developing a
manufacturable approach to real devices," said Rogers. "For this
purpose, we are finalizing printers that are capable of handling
substrates with sizes up to 300 x 400 mm."
The researchers are also collaborating with large companies on
developing unusual imaging systems including hemispherical curved focal
plane arrays, and on structural health monitoring devices for aerospace
applications. A recently founded company, Semprius, will commercialize
the technology for "certain key applications".
The researchers reported their work in Science.
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nanotechweb.org/articles/news/6/1/2/1
4 January 2007
A team from the University of Illinois, Urbana-Champaign, US, has come
up with a printing technique that is able to combine layers of
dissimilar semiconductors, such as single-walled carbon nanotubes and
micro- and nanoscale forms of gallium nitride, silicon and gallium
arsenide, on a range of substrates. The method can create ultrathin
multilayer stacks of thin-film transistors, photodiodes, metal oxide
semiconductor field-effect transistors (MOSFETs) and other components.
FET
"We are interested in unusual classes of electronic devices that cannot
be achieved easily with conventional, wafer-based approaches," John
Rogers of the University of Illinois, Urbana-Champaign told
nanotechweb.org. "Examples include mechanically flexible circuits for
paperlike displays, heterogeneously integrated electronics for
communication or imaging devices, and large area electronics for
structural health monitoring. We believe that the electronics necessary
for these sorts of applications can be achieved by combining printing
techniques with semiconductor nanomaterials."
To make the devices, first the team synthesized nanomaterials such as
single-walled carbon nanotubes, and aligned arrays of single-crystal
nanoscale wires and ribbons of gallium nitride, silicon and gallium
arsenide. In the next step, an elastomeric stamp-based printing
technique transferred the nanomaterials to a device substrate.
The method used a stamp of polydimethylsiloxane - laminating this
against the nanomaterial created van der Waals adhesion contacts and
enabled removal of the material from the source substrate. Applying the
resulting "inked" stamp to a device substrate covered with a thin layer
of liquid prepolymer transferred the nanomaterial to the device
substrate. The team then cured the polymer to make the transfer
permanent.
The method suits device substrates such as flexible plastic, glass
plates or semiconductor wafers. What's more, there is no need for
epitaxial growth or wafer bonding.
"In this approach, the integration of the active materials with the
target substrate, which might include low temperature plastic, can occur
in an additive fashion and at room temperature," said Rogers.
Following processing such as adding gate dielectrics, electrodes and
interconnects, the printing process can be repeated to add further
layers of nanomaterial.
"For flexible electronics, these approaches enable much higher device
performance than can be achieved with organic semiconductors," said
Rogers. "For heterogeneous and 3D electronics, the techniques can avoid
some of the challenges and limitations associated with wafer bonding and
epitaxial growth. The resulting systems that we demonstrate - i.e. high
performance, heterogeneous electronics on plastic, in 2D or 3D layouts -
are, to the best of our knowledge, unique."
The researchers say they hope to investigate applications that are not
well addressed with established wafer- or glass-based electronics
technologies, such as high-speed communication and imaging devices that
combine compound semiconductors with silicon in unusual ways. "Flexible
displays, and large area electronics for structural and personal health
monitors are other examples," said Rogers. "In a current project, we are
working on electronic eye type imagers. Further out into the future, we
hope that these flexible electronic devices could be used in certain
types of medical implants."
Now the team plans to investigate scale-up and integration of the
technique into realistic prototype applications. "We are, therefore,
focused on activities such as the development of a printer system that
can build backplanes for displays, as a first step to developing a
manufacturable approach to real devices," said Rogers. "For this
purpose, we are finalizing printers that are capable of handling
substrates with sizes up to 300 x 400 mm."
The researchers are also collaborating with large companies on
developing unusual imaging systems including hemispherical curved focal
plane arrays, and on structural health monitoring devices for aerospace
applications. A recently founded company, Semprius, will commercialize
the technology for "certain key applications".
The researchers reported their work in Science.
Index
Next
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