U.S. patent application number 12/081024 was filed with the patent office on 2010-12-23 for carbon nanotube structure and method of vertically aligning carbon nanotubes.
Invention is credited to Tae-Won Jeong, Yong-Wan Jin, Hee-Tae Jung, Jong-Min Kim, Young-Koan Ko.
Application Number | 20100320439 12/081024 |
Document ID | / |
Family ID | 37911461 |
Filed Date | 2010-12-23 |
United States Patent
Application |
20100320439 |
Kind Code |
A1 |
Jin; Yong-Wan ; et
al. |
December 23, 2010 |
Carbon nanotube structure and method of vertically aligning carbon
nanotubes
Abstract
A Carbon NanoTube (CNT) structure includes a substrate, a CNT
support layer, and a plurality of CNTs. The CNT support layer is
stacked on the substrate and has pores therein. One end of each of
the CNTs is attached to portions of the substrate exposed through
the pores and each of the CNTs has its lateral sides supported by
the CNT support layer. A method of vertically aligning CNTs
includes: forming a first conductive substrate; stacking a CNT
support layer having pores on the first conductive substrate; and
attaching one end of the each of the CNTs to portions of the first
conductive substrate exposed through the pores.
Inventors: |
Jin; Yong-Wan; (Seoul,
KR) ; Kim; Jong-Min; (Suwon-si, KR) ; Jung;
Hee-Tae; (Daejeon-si, KR) ; Jeong; Tae-Won;
(Seoul, KR) ; Ko; Young-Koan; (Daejeon-si,
KR) |
Correspondence
Address: |
ROBERT E. BUSHNELL & LAW FIRM
2029 K STREET NW, SUITE 600
WASHINGTON
DC
20006-1004
US
|
Family ID: |
37911461 |
Appl. No.: |
12/081024 |
Filed: |
April 9, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11455192 |
Jun 19, 2006 |
7371696 |
|
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12081024 |
|
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Current U.S.
Class: |
257/10 ;
257/E29.068; 977/742 |
Current CPC
Class: |
Y10S 977/742 20130101;
H01J 1/3048 20130101; B82Y 30/00 20130101; Y10S 977/788 20130101;
Y10S 977/842 20130101; H01L 51/0048 20130101; Y10S 977/70 20130101;
H01J 2201/30469 20130101; B82Y 10/00 20130101 |
Class at
Publication: |
257/10 ;
257/E29.068; 977/742 |
International
Class: |
H01L 29/12 20060101
H01L029/12 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 11, 2005 |
KR |
10-2005-0095497 |
Claims
1. A Carbon NanoTube (CNT) structure, comprising: a substrate; a
CNT support layer stacked on the substrate and having a plurality
of pores arranged therein; and a plurality of CNTs, one end of each
of the CNTs being attached to portions of the substrate exposed
through the plurality of pores and lateral sides of each of the
CNTs being supported by the CNT support layer.
2. The CNT structure of claim 1, wherein a Self-Assembled Monolayer
(SAM) comprising a functional group having a chemical affinity for
the plurality of CNTs is arranged on the surface of the substrate,
and wherein one end of each of the CNTs is attached to the SAM
through the plurality of pores.
3. The CNT structure of claim 2, wherein the SAM comprises an
organic material containing phosphorous.
4. The CNT structure of claim 3, wherein the organic material
containing phosphorous comprises 2-carboxyethyl phosphoric
acid.
5. The CNT structure of claim 2, wherein the CNT support layer
comprises a colloid monolayer including a plurality of
self-assembled colloid particles and wherein the plurality of pores
are arranged between the colloid particles.
6. The CNT structure of claim 5, wherein the colloid particles
comprise either silica or polystyrene.
7. The CNT structure of claim 2, wherein the substrate comprises a
conductive material.
8. The CNT structure of claim 7, wherein the conductive material
comprises Indium Tin Oxide (ITO).
9-16. (canceled)
Description
CLAIM OF PRIORITY
[0001] This application makes reference to, incorporates the same
herein, and claims all benefits accruing under 35 U.S.C. .sctn.119
from an application for CARBON NANOTUBES STRUCTURE AND VERTICAL
ALIGNMENT METHOD OF THE CARBON NANOTUBES earlier filed in the
Korean Intellectual Property Office on the 11 Oct. 2005 and there
duly assigned Serial No. 10-2005-0095497.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a Carbon NanoTube (CNT)
structure and a method of manufacturing CNTs, and more
particularly, to a CNT structure having CNTs vertically aligned on
a substrate and a method of vertically aligning the CNTs.
[0004] 2. Description of the Related Art
[0005] Since the unique structural and electrical characteristics
of CNTs were known, CNTs have been used for a variety of devices
such as Field Emission Devices (FEDs), back-lights for Liquid
Crystal Displays (LCDs), nanoelectronic devices, actuators and
batteries.
[0006] FEDs are devices that emit light by emitting electrons from
an electron emitting source formed on a cathode and by allowing the
electrons to collide with and excite a phosphor layer coated on an
anode. Recently, CNTs having excellent electron emitting
characteristics have been used as electron emitting sources of
FEDs. To manufacture an improved FED, the CNTs used for the
electron emitting source should have a low driving voltage and a
high emission current. For that purpose, the CNTs need to be
vertically aligned on the cathode.
[0007] Methods of aligning CNTs can be divided into a direct
growth-aligning method and an after-growth-aligning method. The
direct growth-aligning method can realize a high density nano
structure where CNTs are aligned very well by Chemical Vapor
Deposition (CVD), but has a disadvantage in needing high
temperature processing, so that the direct-growth aligning method
has great limitations in applications to electronic devices that
use the CNTs.
[0008] The after-growth-aligning method includes a method of
stacking CNTs through chemical modification of a substrate surface
and a method of aligning CNTs using an electric field or a magnetic
field. A method has been studied to characterize the surface of a
substrate using a variety of lithography processes and selectively
arrange CNTs thereon. However, the after-growth-aligning method has
difficulty in vertically aligning the CNTs on the substrate.
Recently, there has been research with regard to vertically
aligning the CNTs on the substrate using chemical bonding through
chemical modification of the substrate and the CNTs. However, it
has been known that these methods of aligning the CNTs have lots of
problems due to the high aspect ratios of the CNTs.
SUMMARY OF THE INVENTION
[0009] The present invention provides a Carbon NanoTube (CNT)
structure having CNTs vertically aligned on a substrate and a
method of vertically aligning the CNTs.
[0010] According to one aspect of the present invention, a CNT
structure is provided including: a substrate; a CNT support layer
stacked on the substrate and having a plurality of pores arranged
therein; and a plurality of CNTs, one end of each of the CNTs being
attached to portions of the substrate exposed through the plurality
of pores and lateral sides of each of the CNTs being supported by
the CNT support layer.
[0011] A Self-Assembled Monolayer (SAM) including a functional
group having a chemical affinity for the plurality of CNTs is
preferably arranged on the surface of the substrate, and one end of
each of the CNTs is preferably attached to the SAM through the
plurality of pores.
[0012] The SAM preferably includes an organic material containing
phosphorous. The organic material containing phosphorous preferably
includes 2-carboxyethyl phosphoric acid.
[0013] The CNT support layer preferably includes a colloid
monolayer including a plurality of self-assembled colloid particles
and the plurality of pores are arranged between the colloid
particles. The colloid particles preferably include either silica
or polystyrene.
[0014] The substrate preferably includes a conductive material. The
conductive material preferably includes Indium Tin Oxide (ITO).
[0015] According to another aspect of the present invention, a
method of vertically aligning Carbon NanoTubes (CNTs) is provided,
the method including: forming a first conductive substrate;
stacking a CNT support layer having a plurality of pores on the
first conductive substrate; and attaching one end of the each of
the CNTs to portions of the first conductive substrate exposed
through plurality of pores.
[0016] The method preferably further includes forming a
Self-Assembled Monolayer (SAM) including a functional group having
a chemical affinity for the plurality of CNTs on the surface of the
first conductive substrate after its formation. The SAM is
preferably formed of an organic material containing phosphorous.
The organic material containing phosphorous preferably includes
2-carboxyethyl phosphoric acid.
[0017] Stacking of the CNT support layer preferably includes
forming a colloid monolayer including a plurality of self-assembled
colloid particles on the SAM, and forming the plurality of pores
between the colloid particles. The colloid particles are preferably
formed of either silica or polystyrene.
[0018] Attaching one end of each of the CNTs preferably includes:
arranging a second to conductive substrate spaced a predetermined
distance from a surface of the first conductive substrate on which
the colloid monolayer has been formed; injecting a dispersion
solution to disperse the CNTs between the first and second
conductive substrates; attaching one end of each of the CNTs
contained in the dispersion solution to the SAM using the plurality
of pores formed between the colloid particles by applying an
electric field between the first conductive substrate and the
second conductive substrate; and removing the dispersion solution
with a solvent.
[0019] An anode voltage and a cathode voltage are preferably
respectively supplied to the first conductive substrate and the
second conductive substrate to produce the electric field.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] A more complete appreciation of the present invention and
many of the attendant advantages thereof, will be readily apparent
as the present invention becomes better understood by reference to
the following detailed description when considered in conjunction
with the accompanying drawings in which like reference symbols
indicate the same or similar components, wherein:
[0021] FIG. 1 is a view of a Carbon NanoTube (CNT) structure
according to an embodiment of the present invention;
[0022] FIGS. 2A through 2D are views of a method of vertically
aligning CNTs so as to manufacture the CNT structure of FIG. 1;
[0023] FIG. 3 is a Scanning Electron Microscope (SEM) photo of a
colloid monolayer formed on a Self-Assembled Monolayer (SAM);
[0024] FIG. 4 is an SEM photo of vertically aligned CNTs arranged
between colloid particles; and
[0025] FIG. 5 is a view of the electric field emission
characteristics of an Field Emission Device (FED) having a CNT
structure according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0026] The present invention is described more fully below with
reference to the accompanying drawings, in which exemplary
embodiments of the present invention are shown. Like reference
numerals in the drawings denote like elements. The invention can,
however, be embodied in many different forms and should not be
construed as being limited to the embodiments set forth herein.
Rather, these embodiments are provided so that this disclosure will
be thorough and complete, and will fully convey the concept of the
present invention to those skilled in the art.
[0027] FIG. 1 is a perspective view of a Carbon NanoTube (CNT)
structure according to an embodiment of the present invention.
[0028] Referring to FIG. 1, a predetermined material layer is
formed on the surface of a substrate 110 so that one end of each of
the CNTs 140 can be attached well thereon. The substrate 110 can be
formed of a conductive material, such as Indium Tin Oxide (ITO).
According to an embodiment of the present invention, the material
layer can be a Self-Assembled Monolayer (SAM) 120 including a
function group having affinity for the CNTs 140. The SAM 120 can be
formed of an organic material containing phosphorous, such as
2-carboxyethyl phosphoric acid.
[0029] A CNT support layer is formed on the SAM 120. The CNT
support layer includes a to plurality of pores exposing the SAM
120. According to an embodiment of the present invention, the CNT
support layer can be a colloid monolayer 130 formed on the SAM 120.
The colloid monolayer 130 includes a plurality of self-assembled
colloid particles 131. Also, the pores exposing the SAM 120 are
formed between the colloid particles 131. The colloid particles 131
can be formed of silica or polystyrene.
[0030] One end of each of the CNTs 140 are attached on the portions
of the SAM 120 exposed through the pores formed between the colloid
particles 131. Since the lateral sides of the CNTs 140 having large
aspect ratios are supported by the colloid particles 131, the CNTs
140 can be vertically aligned on the substrate 110 having the SAM
120 thereon with the help of the pores formed between the colloid
particles 131.
[0031] Though the SAM 120 including a functional group having
affinity for the CNTs 140 is formed on the surface of the substrate
110 in the present embodiment, the SAM cannot be formed but one end
of each of the CNTs 140 can be directly attached to the portions of
the substrates 110 exposed through the pores between the colloid
particles. Also, though the colloid monolayer 130 including a
plurality of colloid particles 131 is used for a CNT support layer
in the present invention, a predetermined material layer having a
plurality of pores therein can be used.
[0032] A method of vertically aligning the CNTs so as to
manufacture the CNT structure is described below. FIGS. 2A through
2D are views of the method of vertically aligning the CNTs so as to
manufacture the CNT structure.
[0033] Referring to FIG. 2A, a first conductive substrate 110 is
provided. The first conductive substrate 110 can be the substrate
described in the above embodiment. The first to conductive
substrate 110 can be formed of a transparent conductive material,
such as ITO. Also, a SAM 120 including a function group having
affinity for the CNTs (140 in FIG. 2D) is formed on the first
conductive substrate 110. The SAM 120 can be formed of an organic
material containing phosphorous, such as 2-carboxyethyl phosphoric
acid. In detail, the SAM 120 can be formed by making 5 mM of
2-carboxyethyl phosphoric acid and immersing the first conductive
substrate 110 in this solution for a predetermined period of
time.
[0034] Referring to FIG. 2B, a CNT support layer having a plurality
of pores therein is formed on the SAM 120. According to an
embodiment of the present invention, the CNT support layer can be a
colloid monolayer 130 formed on the SAM 120. The colloid monolayer
130 includes a plurality of self-assembled colloid particles 131.
Also, the pores exposing the SAM 120 are formed between the colloid
particles 131. The colloid particles 131 can be formed of silica or
polystyrene. In detail, silica particles having uniform nano sizes
of about 570 nm are dispersed in a propanol solution and then this
solution is spin-coated on the first conductive substrate 110 on
which the SAM 120 is formed, so that the colloid monolayer 130
including a plurality of self-assembled colloid particles 131 can
be formed on the SAM 120. A Scanning Electron Microscope (SEM)
photo in FIG. 3 shows the colloid monolayer 130 formed on the SAM
120.
[0035] Referring to FIG. 2C, a second conductive substrate 150 is
arranged to be spaced a predetermined distance from the first
conductive substrate 110 on which the colloid monolayer 130 is
formed. The second conductive substrate 150 can be formed of a
transparent conductive material, such as ITO. Also, a dispersion
solution 160 dispersing the CNTs (140 in FIG. 2) therein is
injected between the first conductive substrate 110 and the second
conductive substrate 150. When the first and second conductive
substrates 110 and 150 are spaced a small distance, e.g., 1-1.5 mm
from each other, the dispersion solution 160 can be injected
between the first conductive substrate 110 and the second
conductive substrate 150 by capillary action.
[0036] Subsequently, when a predetermined anode voltage and cathode
voltage are respectively supplied to the first conductive substrate
110 and the second conductive substrate 150, an electric field is
generated between the first conductive substrate 110 and the second
conductive substrate 150. Also, one end of each of the CNTs 140
contained in the dispersion solution 160 are attached to the
portions of the SAM 120 exposed through the pores formed between
the colloid particles 131 by the electric field. At this point,
since the SAM 120 includes a function group having affinity for the
CNTs 140, one end of each of the CNTs 140 are stably attached to
the SAM 120 by chemical bonding. Also, the lateral sides of the
CNTs 140 having large aspect ratios are supported by the colloid
particles 131, so that the CNTs 140 can be vertically aligned on
the substrate 110 having the SAM thereon.
[0037] Lastly, when the dispersion solution 160 and the second
conductive substrate 150 are removed, the CNTs 140 remain
vertically aligned through the pores on the substrate 110 having
the colloid monolayer 130 thereon as illustrated in FIG. 2D. FIG. 4
is an SEM photo showing CNTs 140 which are vertically aligned
between colloid particles 131.
[0038] According to the inventive method for vertically aligning
the CNTs, one end of each of the CNTs 140 having large aspect
ratios are attached to the substrate 110 through the pores between
the colloid particles 131 and the lateral sides of the CNTs 140 are
supported by the colloid particles 131, so that the CNTs 140 can be
vertically aligned at predetermined positions on the substrate
110.
[0039] The CNT structure manufactured by the method of vertically
aligning the CNTs according to an embodiment of the present
invention can be applied to a variety of electronic devices, and in
particular, usefully applied to an electron emitting source of an
FED.
[0040] FIG. 5 illustrates results obtained by measuring the
electric field emission characteristics of an FED that uses the CNT
structure according to an embodiment of the present invention.
Referring to FIG. 5, it is revealed that a current density required
for the FED can be obtained by properly changing the intensity of
an electric field applied between a cathode and an anode.
[0041] As described above, the present invention has the following
effects.
[0042] First, a colloid monolayer including a plurality of colloid
parties is formed on the substrate, so that one end of each of the
CNTs 140 having large aspect ratios are attached to the substrate
110 through the pores formed between the colloid particles 131 and
the lateral sides of the CNTs 140 are supported by the colloid
particles 131. Therefore, the CNTs 140 can be vertically aligned at
predetermined positions on the substrate 110.
[0043] Second, the method of vertically aligning the CNTs according
to an embodiment of the present invention can vertically align the
CNTs using a simple process that can be applied to the manufacture
of a large-sized FED. Also, since the method does not require a
high temperature process, the present invention has a small
limitation for temperature.
[0044] Third, the CNTs can be vertically aligned on the substrate
using a small amount of CNTs. In detail, according to the inventive
method of vertically aligning the CNTs, an amount of about 0.2
.mu.g of CNTs is required for vertically aligning the CNTs on an
area 1 cm.sup.2 of the substrate. Therefore, it is possible to
manufacture a 40-inch FED using only 1 mg of CNTs.
[0045] While the present invention has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be understood by those of ordinary skill in the art that various
modifications in form and detail can be made therein without
departing from the spirit and scope of the present invention as
defined by the following claims.
* * * * *