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Nanoscopic wire-based devices and arrays

a wire-based device and array technology, applied in nanoelectromechanical switches, instruments, relays, etc., can solve the problems of preventing current designs from functioning reliably, and reducing the size limitation of silicon-based microelectronics, so as to achieve the fundamental physical limitations of both device elements and wire interconnects, and preventing current designs from being made small

Inactive Publication Date: 2005-06-02
PRESIDENT & FELLOWS OF HARVARD COLLEGE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a series of nanoscopic-scale electronic elements, methods of making nanoscopic-scale electronic devices, and methods of using nanoscopic-scale electronic devices. The invention involves creating electronic devices with nanoscopic wires, such as nanotubes, that can be used in crossbar arrays or memory elements. The invention has various advantages, including high density and the ability to switch between states. The technical effects of the invention include the creation of small, efficient electronic devices with improved performance and reliability.

Problems solved by technology

Silicon-based microelectronics, however, can be made only so small.
That is, there is a size limitation smaller than which silicon-based microelectronics cannot be fabricated.
First, fundamental physical limitations will be reached for both device elements and wire interconnects that will prevent current designs from functioning reliably.
Second, the concurrent exponential increase in fabrication (FAB) facility cost is expected to make it uneconomical to consider increasing integration levels further (using silicon technology) even if it is physically meaningful.

Method used

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  • Nanoscopic wire-based devices and arrays
  • Nanoscopic wire-based devices and arrays
  • Nanoscopic wire-based devices and arrays

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0093] To quantify the bistability and switching behavior of the device element a total energy, ET, can be calculated:

ET=Evdw+Eelas+Eelec   (1)

where Evdw is the van der Waals (vdW) energy, Eelas is the elastic energy and Eelec is the electrostatic energy for the device. The first two terms in (1), which define the static potential, can be evaluated to assess the range of parameters that yield bistable devices. FIG. 11 shows plots of energy, ET=EvdW+Eelas, for a single 20 nm device as a function of separation at the junction. The series of curves correspond to initial separations of 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4 nm for carbon nanotubes, with two well-defined minima observed for initial separations of 1.0 to 2.0 nm. These minima correspond to the crossing nanotubes being separated (2.4 nm) and in vdW contact (0.8 nm). The vdW interaction between nanotubes can be calculated by pairwise summation of a Lennard-Jones potential that has been shown previously to provide goo...

example 2

[0095] The effectiveness of switching the suspended nanotube devices between on and off states has been assessed by evaluating the voltage-dependent contribution of the electrostatic energy to the total energy. In this calculation, the boundary element method was used to numerically solve the Laplace equation for the complex three-dimensional geometry of the crossed nanotube device. Calculations of ET for switching a 20 nm device on and off (FIG. 15) demonstrate that it is possible to change reversibly between the on / off states using moderate voltages, which do not exceed the threshold field for nanotube failure. The switching voltages vary depending on the specific device geometry (i.e., shape of the static potential), and thus can be further optimized. For example, by using a thinner dielectric layer (that is, 4 vs 20 nm SiO2) the on and off switching thresholds can be reduced from 4.5 and 20 V to 3 and 5 V, respectively. The calculations also show that the electrostatic forces be...

example 3

[0097] Administration of reversible switching and the ability of the device to function as a non-volatile RAM is provided in this Example. Properties of suspended, crossed nanotube devices made from SWNT ropes were studied by mechanical manipulation (FIG. 16). Current-voltage (I-V) measurements made on the lower and upper nanotubes of a typical model device show ohmic behavior with resistances of 11 and 58 kΩ, respectively (FIG. 16A). The I-V curves between the upper and lower ropes in the off state were nonlinear, which is consistent with tunneling, with a resistance on the order of a GΩ. After switching on, the I-V curves exhibited ohmic behavior with a resistance of 112 kΩ (FIG. 16B). This large change in resistance is consistent with our predictions for off vs. on states in the suspended device architecture. Reversible switching between well-defined on / off states has also been observed in devices (FIG. 17). The smaller change in on / off resistances for the device in FIG. 17 is be...

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Abstract

Electrical devices comprised of nanoscopic wires are described, along with methods of their manufacture and use. The nanoscopic wires can be nanotubes, preferably single-walled carbon nanotubes. They can be arranged in crossbar arrays using chemically patterned surfaces for direction, via chemical vapor deposition. Chemical vapor deposition also can be used to form nanotubes in arrays in the presence of directing electric fields, optionally in combination with self-assembled monolayer patterns. Bistable devices are described.

Description

RELATED APPLICATIONS [0001] This application is a continuation of International Patent Application Serial No. PCT / US00 / 18138, filed Jun. 30, 2000, which claims priority to U.S. Provisional Patent Application Ser. No. 60 / 142,216, filed Jul. 2, 1999.GOVERNMENT SPONSORSHIP [0002] This invention was sponsored by NIH Grant No. GM30367. The government has certain rights in the invention.FIELD OF THE INVENTION [0003] The present invention relates generally to the controlled formation and / or orientation of large molecules, such as nanotubes, on surfaces, and more particularly to formation of carbon nanotubes on surfaces for making nanoscopic-scale electronic devices such as memory arrays, configurable logic and other computer elements. BACKGROUND OF THE INVENTION [0004] During the past several decades there has been a nearly constant exponential growth in the capabilities of silicon-based microelectronics leading, for example, to tremendous advances in our computational capabilities. Silico...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B82B1/00B82B3/00G11C13/02G11C23/00H01H59/00H01L27/10H01L27/24H01L29/06H01L29/66H01L51/00H01L51/30H10N99/00
CPCB82Y10/00Y10S977/943B82Y30/00B82Y40/00G11C13/025G11C23/00G11C2213/16G11C2213/72G11C2213/77G11C2213/81H01H1/0094H01L27/10H01L27/285H01L51/0048H01L51/0052H01L51/0595Y10S977/762Y10S977/932Y10S977/75Y10S977/843Y10S977/936B82Y15/00H10K85/221H10K85/615H10K10/701H10K39/30H10B99/10H10K19/202
Inventor LIEBER, CHARLES M.RUECKES, THOMASJOSELEVICH, ERNESTOKIM, KEVIN
Owner PRESIDENT & FELLOWS OF HARVARD COLLEGE
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