Fabrication of cacbon nanotube based field effect transistors for DNA sensor application

Fabrication of cacbon nanotube based field effect transistors for DNA sensor application Fabrication of cacbon nanotube based field effect transistors for DNA sensor application Fabrication of cacbon nanotube based field effect transistors for DNA sensor application luận văn tốt nghiệp,luận văn thạc sĩ, luận văn cao học, luận văn đại học, luận án tiến sĩ, đồ án tốt nghiệp luận văn tốt nghiệp,luận văn thạc sĩ, luận văn cao học, luận văn đại học, luận án tiến sĩ, đồ án tốt nghiệp

Ministry of Education and Training Hanoi University of Science and Technology International Training Institute for Material Science PHUONG TRUNG DUNG FABRICATION OF CARBON NANOTUBE BASED FIELD EFFECT TRANSISTORS FOR DNA SENSOR APPLICATION MASTER OF SCIENCE THESIS Supervisors: DR PHUONG DINH TAM DR MAI ANH TUAN Hanoi – 2012 Master of Science Thesis Hanoi University of Science and Technology ACKNOWLEDGEMENTS First of all, I give deepest thank to my two supervisors, Dr Mai Anh Tuan and Dr Phuong Dinh Tam for giving me the opportunity to study on carbon nanotube electronic matter, thank you for your patience, support, faith, and encouragement My thanks and honors to my lectures at Hanoi University of Science and Technology for mentoring me, and teaching me new things during my two years in master program at ITIMS I wish to thank to the old and new members of research groups in ITIMS, especially biosensor and gas sensor group, who share valuable experiences and help me a lot with kindness and friendship My family, my friends, thank you for the joyful times, unforgettable moments, and thank for being my patient companions during all times Phuong Trung Dung 2010 – 2012 Master of Science Thesis Hanoi University of Science and Technology SUMMARY The incidence of diseases cause by harmful pathogen has increased in recent years that threaten human lives Their appearance causes serious morbidity and immune-compromised to people Therefore, in require of society, many methods have been proposed so far to detect these pathogens The conventional culture is a standard method which very sensitive and inexpensive and can give both qualitative and quantitative information regarding the analytical present in a sample However, it cost time and require skilled labor The molecular biology-based methods are highly specific and accurate but costly and also time-consuming A simple, reliable device for analytical application has been developed as alternative Bio-sensing technology started to be most used method after PCR and ELISA due to many advantages including small sized, high sensitivity, short detecting time at low cost The general objective of this thesis is the development of DNA sensor applying for detection of E Coli bacteria in which SWNTs are used as the transducer elements The sensor will be prepared by deposition of functionalized SWNT over patterned metal electrodes of a silicon wafer which had been prefabricated by simple photolithography The molecular recognition mechanism lies in DNA-DNA hybridization in which single strand DNA probe/SWNT act as the sensing layers This thesis is organized into three chapters - Chapter will cover the essential theoretical background; start with brief introduction on physic of carbon nanotube and some of the detail of the physic for example hybridization Then, the short overview of the single Phuong Trung Dung 2010 – 2012 Master of Science Thesis Hanoi University of Science and Technology walled carbon nanotube based transistor (SWNTFET) is introduced Its basic properties such as electrical transport, SWNT-metal interfaces and gate hysteresis also presented - Chapter will summarize the preparation process of the SWCNFET sensors and functionalization of carbon nanotube for final device Further, the electrical measurement setup and its used is introduced - Chapter after completely preparation, SWNTFET is applied to the detection of E Coli virus sample The results characteristics will be analyze and discuss - Finally, concludes of the whole thesis and the long-term propose or recommendation for future work will be given Phuong Trung Dung 2010 – 2012 Master of Science Thesis Hanoi University of Science and Technology TABLE OF CONTENTS ACKNOWLEDGEMENTS SUMMARY LIST OF SYMBOL 10 LIST OF FIGURES 12 LIST OF EQUATIONS 16 LIST OF TABLES 17 CHAPTER 20 FUNDAMENTAL 20 1.1 Introduction to Carbon nanotubes 20 1.1.1 Electronic structure 20 1.1.2 Band structure 22 1.1.3 Electron mobility 24 1.2 Introduction to deoxyribonucleic acid (DNA) 25 1.2.1 DNA structure 25 1.2.2 Hybridization properties 26 1.3 Introduction to Carbon nanotube field-effect transistor (CNTFET) 27 1.3.1 The origins, MOSFET 27 Phuong Trung Dung 2010 – 2012 Master of Science Thesis Hanoi University of Science and Technology 1.3.2 CNTFET structure 29 1.3.3 CNTFET Working principle 29 1.3.4 Type of CNTFET 33 1.3.5 Application of CNTFET in biosensor 37 1.3.6 Conclusion 42 CHAPTER 43 EXPERMENTAL 43 2.1 Reagents 43 2.2 SWNTFET preparation 44 2.2.1 Mask design 44 2.2.2 Sensor fabrication process 45 2.2.3 Nanotube deposition on sensor surface 49 2.3 Equipment and measurement setup 51 2.3.1 Semiconductor parameter analyzer, Keithley 4200 52 2.3.2 Measurement setup 52 CHAPTER 54 RESULS AND DISSCUSSION 54 3.1 Device characteristics 54 3.1.1 Id-Vds characteristics of SWNTFET 54 Phuong Trung Dung 2010 – 2012 Master of Science Thesis Hanoi University of Science and Technology 3.1.2 Id-Vgs characteristics of SWNTFET 55 3.1.3 Influence of environment exposing to sensor 57 3.2 SWNT – DNA immobilization characteristics 59 3.2.1 Dispersion of SWNTs in DNA solution 59 3.2.2 UV-Vis spectra characterization of SWNTs dispersed in DNA solution 60 3.2.3 Morphology of SWNTs dispersed in DNA solution 62 3.2.4 FTIR spectra of SWNT – DNA films 62 3.3 Id-Vgs characteristics of probe DNA immobilization onto sensor 63 3.4 Label – free detection of DNA sequences using SWNTFETs 64 3.4.1 Ids-Vds characteristics 64 3.4.2 Sensitivity and response time of the sensor 66 CONCLUSION 68 REFERENCE 69 ARTICLES 75 Phuong Trung Dung 2010 – 2012 Master of Science Thesis Hanoi University of Science and Technology LIST OF ABREVIATIONS AFM Atomic Force Microscopy Al Aluminum CNT Carbon Nanotube CNTFET Carbon Nanotube Field-Effect Transistor Cr Chromium DNA Deoxyribonucleic Acid FET Field Effect Transistor HF Hydrofluoric Acid HNO3 Nitric Acid HRTEM High Resolution Transmission Electron Microscope H O2 Hydrogen peroxide H2SO4 Sulfuric acid HUST Hanoi University of Science and Technology ITIMS International Training Institute for Material Science MFP Mean Free Path MOSFET Metal Oxide Semiconductor Field-Effect Transistor MWNT Multi Walled Carbon Nanotube N2 Nitrogen molecule Phuong Trung Dung 2010 – 2012 Master of Science Thesis Hanoi University of Science and Technology NTFET Nanotubes Field-Effect Transistor Pd Palladium Pt Platinum SB Schottky Barrier SBH Schottky Barrier Height S/D Source/Drain SEM Scanning Electron Microscope Si Silicon SiO2 Silicon Dioxide ssDNA Single-strand Deoxyribonucleic Acid SWNT Single Walled Carbon Nanotube s-SWNT Semiconducting Single Walled Carbon Nanotube m-SWNT Metallic Single-Walled Carbon Nanotube SWNTFET Single Walled Carbon Nanotube Field Effect Transistor TMAH Tetramethyl Ammonium Hydroxide Phuong Trung Dung 2010 – 2012 Master of Science Thesis Hanoi University of Science and Technology LIST OF SYMBOL a Length of graphene lattice unit vectors C-C Carbon-carbon E Energy state EF Fermi level Eg Band Gap G0 Conductance quantum (= 2q2/h = 77.5 µS) h Planck constant (6.626 10 34 m2kg/s) Id Drain-Source Current Ioff Off-Current Ion On-Current kb Boltzmann constant Lnom Nominal device channel length (n,m) SWNT integers ΦB, n Potential barrier for electrons at the semiconductor/metal contact ΦB, P Potential barrier for holes at the semiconductor/metal contact ΦM Metal work function ΦSWNT Work function 10 Phuong Trung Dung 2010 – 2012 Master of Science Thesis Hanoi University of Science and Technology SWNTs in DNA solution at different dispersion times (i.e., from 10 to 120 min) Absorption intensity is directly proportional to dissolved time As mentioned above, the dispersion of SWNTs allows a coulomb interaction to occur between the DNA sequence and the SWNTs Yu et al., [32] reported that at the start of sonication, the SWNTs are of the same size as the big bundles in the solution impeding the absorption of the UV-Vis spectrum The sonication process creates mechanical energy, which can overcome the van der Waals interactions in the CNT aggregation and disperse them Thus, the intensity of the absorption increases with increasing dissolving time In other words, the SWNT is well dispersed in the DNA solution We found that 120 of sonication time is necessary for the entire sample to reach a stable stage for SWNTs in DNA solution Figure 3.5: UV-Vis spectra of dispersed SWNTs in DNA solution at different sonication times (I) and pH values (II) (Power: 125 W, 20 mM DNA, 15 mg CNTs) Fig.3.5 (II) illustrates the UV-Vis spectra of dispersed SWNTs in DNA solution for 120 at pH 3, pH 7, pH 9, and pH 12 The intensity of the absorption peaks drastically decreased at pH and pH 12 This result shows that the SWNT dispersion is not stable At pH and pH 9, SWNTs are well dispersed and stabilized This result can be explained by the instability of the DNA sequence at pH and pH 12 This instability disrupts the interaction between the DNA sequence and the SWNTs, and thus decreases the dispersion of SWNTs in DNA solution 61 Phuong Trung Dung 2010 – 2012 Master of Science Thesis Hanoi University of Science and Technology 3.2.3 Morphology of SWNTs dispersed in DNA solution The morphology of dispersed SWNTs was studied using FE-SEM and TEM (Figure 3.6) FE-SEM samples were prepared by dropping an aqueous dispersion of SWNTs in a silicon substrate and drying at room temperature for h The TEM sample was prepared by dipping a copper TEM grid in the SWNT dispersion and subsequently drying it The FE-SEM image of the dispersed SWNT sample shows that the individual SWNTs on the substrate surface and the unique tube-like structure were well maintained (Figure 3.6 a) The TEM image with the CNTs bundles (Figure 3.6 b) was divided into thinner bundles and single nanotubes Figure 3.6: FE-SEM (a) and TEM (b) images of CNTs dispersed in DNA solution after months (power: 125 W, 20 mM DNA, pH7, 15 mg CNTs, 120 min) 3.2.4 FTIR spectra of SWNT – DNA films The structure of dispersed SWNTs in DNA solution was studied through FTIR spectrum The FTIR spectra of pristine SWNTs and dispersed SWNTs in the range of 700 cm-1 to 2000 cm-1 are presented in Figure 3.7 In the pristine sample shown in Figure 3.7 a, the band at 1050 cm-1 was assigned to C–N bonding due to HNO3 acid treatment The spectra of C=C stretching vibration was at approximately 1640 cm-1 The peak from 931 cm-1 to 985 cm-1 was assigned to the stretching mode of aromatic amine groups Figure 3.7 b shows the FTIR spectra of pure DNA The symmetrically stretched peak at 1054 cm-1 was due to the phosphate of the DNA The peaks at 62 Phuong Trung Dung 2010 – 2012 Master of Science Thesis Hanoi University of Science and Technology 1700, 1580, and 1348 cm-1 were due to thymine, adenine, and guanine bases, respectively [16] Figure 3.7: The FTIR spectra of the SWNTs (a), nature DNA (b), DNA-CNT complex (c), power: 125 W, 20 mM DNA, pH7, 15 mg CNTs, 120 Figure 3.7 c shows the results of DNA absorption on the SWNT surface The bands at 1650, 1210, and 1660 cm-1 were assigned to the amine group (NH2), the phosphate asymmetric stretching vibration of the mixtures, and the adenine base of the DNA sequence, respectively The peak at 1350 cm-1 was due to guanine, and the peak at 1450 cm-1 to 1480 cm-1 was due to the cytosine of the DNA sequence Minor shifting of the C–N band was observed from 1050 cm-1 to 1060 cm-1, and aromatic amine groups were detected from 927 cm-1 to 984 cm-1 In this case, the – CO2 and C=C bands at 1120 and 1640 cm-1 did not exhibit shifting upon dispersion, respectively 3.3 Id-Vgs characteristics of probe DNA immobilization onto sensor Figure 3.8 presents Id - Vgs characterization of sensor before and after being immobilized with the probe DNA The gate voltage was scanned from -14 V to V at fixed source - drain bias of 300 mV The channel current and the threshold voltage value of the SWNTFETs have changed slightly The bare SWNTFET shows maximum channel current The 63 Phuong Trung Dung 2010 – 2012 Master of Science Thesis Hanoi University of Science and Technology electrical current decreased in average of 25 nA, and the threshold voltage shift to the left about of 300 mV after the probe DNA immobilization process Figure 3.8: Schematic illustration of drain current dependence of gate voltage after probe immobilization The decrease of the channel current showed that there was negative charge transfers from probe DNA sequences to carbon nanotubes provide electrons to the nanotubes that could change the work function of electrode Otherwise, as mentioned a lot in previous sections, the SWNTs shows PMOS like behavior, then each absorbed amine give a rise of electrons that will make the current to decrease as well as the shift of current towards more negative gate voltage In contrast, the clinging bonds of adsorbed probe strands onto surface give stress to the SWNTs make them to be distorted Or, molecules themselves may act as a scattering center leading to the decrease of mobility, thus, suppressing the current From those results showed that there were significant amounts of probe DNA (ssDNA) attached to the nanotubes 3.4 Label – free detection of DNA sequences using SWNTFETs 3.4.1 Ids-Vds characteristics In previous section 3.3 showed the probe DNA sequences have been attached to SWNTFET This section will demonstrate the capability of SWNTFETs to detect complementary sequences hybridization Mechanism of DNA strands hybridization 64 Phuong Trung Dung 2010 – 2012 Master of Science Thesis Hanoi University of Science and Technology detection is based on specific interaction between probe DNA sequences and its complementary sequences Due to phosphate groups of DNA molecules are negatively charged, when hybridization happens, two DNA sequences bind together and form double helix, leading to increasing of negative charge density of the DNA sequences at sensor surface, resulting in change of effective voltage applied to gate In other words, threshold voltage, VT would be changed that leads to a change in drain current, Id, at the same Vg From the difference of VT or Id, complementary hybridization could be detected A probe DNA immobilized SWNTFET first was immersing the SWNTFETs in PBS solution adding µL of µM complementary DNA for 10 minutes at room temperature, then rinsed thoroughly with DI water and dried with nitrogen Then the device has been electrically characterized by measuring three times the Ids versus Vgs at fixed bias voltage Vds of 300 mV The applied gate voltage is scanned in range of -14 V to V Fig.3.9 described dependence between the gate voltage, Vgs, and source drain current, Id, before and after exposure to target DNA sequences Figure 3.9: Id -Vgs characteristics of complementary target DNA detection, exposed concentration of µM As showed in Fig 3.9, at the same applied voltages, the bare SWNTFET shows the maximum electrical current After the probe DNA sequences immobilization process, channel current is slightly reduced Another, the electrical 65 Phuong Trung Dung 2010 – 2012 Master of Science Thesis Hanoi University of Science and Technology current decreased slightly due to interaction between probe DNA and complementary sequences 3.4.2 Sensitivity and response time of the sensor To investigate the sensitivity to DNA detection, SWNTFETs were exposed to different concentrations of complementary DNA sequences solution of µM, 0.5 µM and 0.05 µM For each concentration, the sensor was immersed for 10 minutes (except at very low concentration of 0.05 µM, it took up to 30 or longer), rinsed thoroughly distilled water, dried with nitrogen and electrically characterized by measuring at least three times the Id-Vgs characteristic The curve plotted by mean value in range of measurement Figure 3.10a shows the Id-Vds characteristic (at fixed Vds bias of 300 mV) of a fabricated SWNTFET exposed to concentration as mentions above (b) (a) Figure 3.10: Id-Vgs characteristic of a fabricated SWNTFET immobilized with probe DNA of E Coli bacteria, hybridized in complementary target sequences analyte of different concentration µM, 0.5 µM, and 0.05 µM (a) sensor sensitivity deduced from concentration dependence of drain current curve (b) The exposure to increasing concentration of target DNA (Fig 3.10a) reduced the conductance of the sensor By other way, the higher the concentration of target DNA, the more the electrical current decreased This can explain as the effect of 66 Phuong Trung Dung 2010 – 2012 Master of Science Thesis Hanoi University of Science and Technology charge transfer process in which electrons donating from the amino groups of DNA strands to CNT channel caused by the hybridization of two complementary strands According to measurement data, the average electrical current decreasing for target DNA concentrations is approximately 75 nA and nA for concentration difference of µM to 0.5 µM and 0.5 µM to 0.05 µM, respectively Then, this device showed a sensitive of 15 to 17 nA per µM of DNA (Fig 3.10b) The response time of sensor depend on the kinetics of DNA hybridization and concentration of analyte (related to diffusion rate) Nevertheless an experiment to determine this reaction time was performed SWNTFET devices were immersed in a solution adding µL of 0.05 µM E Coli complementary strands, 100 times smaller than commonly used After 10 minutes, devices were rinsed thoroughly with water, dried it and measured the electrical current After each measurement the devices were again submerged in the solution for another 10 minutes and electrically characterized The decrease of the current intensity was obtained in approximately 30 minutes The current changed further after that but not significant Figure 3.10b shows the electrical current value versus time characteristic at a specific gate and source-drain voltages (Vgs = -12 V; Vsd = 300 mV) by the same experiment The result suggested that, the electrical current decreased slightly in compare to initial (device with only probe sequences) At this present experiment condition, further reducing the concentration of analyte is limited due to lack of skill and needed equipment Therefore, the response time of devices in this work was chosen as 30 minutes reaction time at low analyte concentration of 0.05 µM 67 Phuong Trung Dung 2010 – 2012 Master of Science Thesis Hanoi University of Science and Technology CONCLUSION The purpose of this thesis is investigation of carbon nanotubes field effect transistor for DNA hybridization detection In this thesis, a review about of CNTFET was mentioned Specially, the DNA biosensor based on CNTFET was reviewed in detail Depending on the existing equipment in research facilities, this thesis selected SWNTFET based on back - gate structure for fabrication of DNA biosensor The application of DNA sensor for determining DNA hybridization was allowed to draw following conclusions: 1) In this thesis, the SWNTFET was successfully fabricated by using microelectronic technique 2) Non-covalent attachment method was used to immobilize probe DNA sequence on carbon wall 3) The using of DNA sensor to determine complementary sequence hybridization showed the DNA sensor based on SWNTFET could determine concentration in minimum of 0.05 µM, the sensitivity of device is approximately 16 nA/µM and sufficient reaction times of 30 minutes Thus, the successful fabrication of SWNTFET and sensor applications for DNA sequence hybridization has fully confirmed that the DNA sensor based on SWNTFET could be fabricated in Vietnam for biomedicine applications 68 Phuong Trung Dung 2010 – 2012 Master of Science Thesis Hanoi University of Science and Technology REFERENCE A Javey, J Guo, D B Farmer, Q Wang, D W Wang, R G Gordon, M Lundstrom, and H J Dai, “Carbon nanotube field-effect transistors with integrated ohmic contacts and high-k gate dielectrics”, Nano Letters, vol 4, pp 447-450, Mar 2004 A Javey, J Guo, Q Wang, M Lundstrom, and H Dai, “Ballistic carbon nanotube field-effect 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193–198, 2003 49 Xiaochen Dong, Dongliang Fu, YanpingXu, JinquanWei,Yumeng Shi, Peng Chen, Lain-Jong, “Label-Free Electronic Detection of DNA Using Simple Double-Walled Carbon Nanotube Resistors” Li, J Phys Chem C, 112, 9891– 9895, 2008 50 Xiaolei Liu et al., “Carbon Nanotube Field-Effect Inverters”, Applied Physics Letters, November 2001 74 Phuong Trung Dung 2010 – 2012 Master of Science Thesis Hanoi University of Science and Technology ARTICLES Phuong Dinh Tam, Nguyen Thi Thuy, Nguyen Sy Uan, Phuong Trung Dung, Vu Van Thu, Mai Anh Tuan, Nguyen Duc Chien, “Dispersion of single wall carbon nanotubes in DNA solution for DNA sensor preparation”, Proceedings of IWNA 2011, November 10-12, 2011, Vung Tau, Vietnam, NMD-055-P, pp 666-669 75 Phuong Trung Dung 2010 – 2012 ... 2010 – 2012 Master of Science Thesis Hanoi University of Science and Technology CHAPTER EXPERMENTAL The focus of this thesis is the construction of a DNA biosensor based on field effect transistor... Morphology of SWNTs dispersed in DNA solution 62 3.2.4 FTIR spectra of SWNT – DNA films 62 3.3 Id-Vgs characteristics of probe DNA immobilization onto sensor 63 3.4 Label – free detection of. .. 2012 Master of Science Thesis Hanoi University of Science and Technology LIST OF ABREVIATIONS AFM Atomic Force Microscopy Al Aluminum CNT Carbon Nanotube CNTFET Carbon Nanotube Field- Effect Transistor