University of Nebraska at Lincoln (Lincoln, NE) scientists have developed a single-electron device composed of a necklace of about 5000 nanoparticles for next generation nano-scale integrated circuits and nanodevices.
A nanoparticle necklace can be shaped to any form required by the circuitization scheme just like copper lines on printed circuit boards. The types of nanoparticles used may be based upon their electrical properties (conducting, insulating, or semiconducting), although other properties such as size or chemistry may be considered. A polymer fiber may be used as a scaffold to direct the assembly of a one-dimensional percolating structure for a nanoparticle necklace. The length and shape of the necklace may be determined by the polymer fiber.
The linear necklace is self-assembled by interfacial phenomena along a triple-phase line of fiber, a substrate and electrolyte containing nanoparticles. A variety of combinations of nanoparticles, such as Au and CdS nanoparticles, may be used to form a necklace. The I-V measurements on the system show both coulomb blockade and staircase, with high currents and high threshold voltage of 1-3 V. U.S. Patent Application 20100120236 details methods for constructing such a device.
According to Nebraska Center for Materials and Nanoscience Professor of Chemical Engineering Ravi F. Saraf, and fellow researchers Sanjun Niu, Vikas Berryand and Vivek Maheshwari, the technique provides a highly resolved, low noise, room temperature Coulomb-staircase and blockade and methods for constructing a Coulomb-staircase and blockade. As the miniaturization continues from micron-scale to nanoscale devices, the nanoparticle necklace can be the next generation approach to make integrated circuit (IC) chip from nanodevices.
The manufacturing method includes: suspending fiber materials in a first solution; spinning the fibers from the solution on a substrate; suspending a first type of nanoparticles in a second solution; immersing the substrate and fibers in the second solution containing the suspended first type of nanoparticles, such that the suspended nanoparticles of the first type adhere to the fibers; suspending a second type of nanoparticle in a third solution; and immersing the substrate, fibers, and adhered nanoparticles of the first type in the third solution, such that the nanoparticles of the second type adhere to the nanoparticles of the first type.
The necklace may utilize a substrate with at least one pair of electrodes. Fibers, such as polystyrene fibers, may be spun out of a solution on the substrate such that a fiber extends across the pair of electrodes. The substrate and fibers may then be immersed in a solution containing suspended nanoparticles of a first type that adhere to the fibers, thereby forming a one dimensional necklace of nanoparticles between the electrodes. The substrate may thereafter be immersed in a solution containing suspended nanoparticles of a second type that adhere to the nanoparticles of the second type.
A variety of types and sizes may be used for these purposes, and nanoparticles may be used alone or in combinations beyond those described herein. Likewise, methods of depositing nanoparticles may differ particularly with regard to the solutions and techniques used to deposit the nanoparticles.