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MINISTRY OF
EDUCATION AND TRAINING
VIETNAM ACADEMY OF
SCIENCE AND TECHNOLOGY
GRADATE UNIVERSITY OF SCIENCE AND TECHNOLOGY

CAO THI THANH
FABRICATION OF ALIGNED CARBON
NANOTUBES AND GRAPHENE MATERIALS
FOR BIOSENSOR APPLICATIONS
Major : Electronic materials
Code : 62.44.01.23
SUMMARY OF DOCTOR THESIS IN MATERIAL SCIENCE
HA NOI - 2018
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The thesis was completed at Key Laboratory for Electronic
Materials and Devices, Institute of Materials Science, Vietnam
Academy of Science and Technology.
Supervisors:
1. Prof. PhD. Tran Dai Lam
2. PhD. Nguyen Van Chuc
Reviewer 1:
Reviewer 2:
Reviewer 3:
The dissertation will be defended at Graduate University of Science
and Technology, 18 Hoang Quoc Viet street, Hanoi.
Time: .............,.............., 2018
The thesis could be found at:
- National Library of Vietnam
- Library of Graduate University of Science and Technology
- Library of Institute of Science Materials
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INTRODUCTION
1. The thesis necessity
Owing to the unique properties such as: larger surface area, high
conductivity, high mechanical stability, excellent electronic mobility,
inert chemical properties in solution and high compatible biological
properties,... carbon nanotubes (CNTs) and graphene materials are
promising to apply in many other fields, such as electronics, energy and
fabrication of ultra-small sensors. In particular, field effect transistor
(FET) and especially ion sensitive field effect transistor (ISFET) using
CNTs/graphene are showed that they have high sensitivity, quick
response time and very low detection limit. This is because the
CNTs/graphene material in the sensor is in direct contact with the
analytical material and directly convert the biological reactions on the
electrode surface into electrical signals. Therefore, a small change of
analytical material could be detected. Some of the sensors based on FET
and ISFET configurations using CNTs and graphene materials have been
launched in the detection of certain substances such as glucose, DNA,
atrazine, E.coli, etc...
In order to improve the potential applications of CNTs and graphene
materials, especially, applications for biosensors, we need control the
quality of materials such as: density, orientation, defection, purity of CNT
as well as the layers, uniform of a graphene film. This is also one of the
major challenges for many research groups in Vietnam and other groups
in the world. For these reasons, we have chosen the topic of thesis is:
“Fabrication of aligned carbon nanotubes and graphene materials
for biosensor applications”
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2. Objectives of the study
i) To find out about orientational CNTs and graphene material: the
formation, methods of synthesis, properties and applications.
ii) Optimization of technological conditions to produce high quality
oriented CNT and graphene materials using the thermal CVD
method.
iii) Application of graphene materials in ISFET- based biosensor to
detect the atrazine pesticide residues.
3. Main research contents of the thesis
i) Fabrication of vertically aligned CNTs (VA-CNTs) and horizontally
aligned CNTs (HA-CNTs) on surface of Si substrate by CVD
method. The effect of parameters: catalysis source gas, the
temperature and catalysis gas source flow on structure, property
and quality of orientational CNTs.
ii) Fabrication of graphene by thermal CVD. The effect of parameters:
temperature, pressure, catalysis gas flow and surface morphology
of catalysis material on the quality of graphene.
iii) Production of field effect transistor based on graphene material
and application of graphene-FET to detect atrazine residues.
4. Thesis structure: This thesis consists of 145 pages: introduction, four
chapters in content, conclusion. The main results were published on 10
journals: 07 articles was published on international journal, 02 article was
published on national journal and 01 presentation at an international
workshop.
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CHAPTER 1:
INTRODUCTION OF CARBON NANOTUBE MATERIAL
This chapter aims to present an overview of CNTs and graphene in
the areas of synthesis, electronic structure, properties, information and
growth mechanisms, analytical technics and applications. We also present
an overview of biosensor such as structure, operation principle as well as
the detection mechanism of the field effect transistors based biosensor
using graphene material to detect atrazine residues.
CHAPTER 2:
FABRICATION OF ORIENTED CARBON NANOTUBE
BY CHEMICAL VAPOR DEPOSITION
2.1 Thermal CVD system used for fabrication of oriented CNTs
Thermal CVD
system used for
fabrication of
oriented CNTs
consist of following
three main parts:
furnace, reaction
chamber and gases
flow control meter
as described in fig.
2.1.
2.2 Fabrication of VA-CNTs material
2.2.1 Preparation of substrate and catalyst material
The silicon substrate with SiO2 layer of 90 nm used to deposit the
catalyst particles. The substrate were cut into small pieces of 5 mm
5 mm and cleaned before coating catalyst on the surface.
Figure 2.1. The CVD system for fabrication
CNTs and graphene at Laboratory of carbon
nanomaterials, Institute of Materials Science