This dissertation includes two major sections. The first section (Chapter 2) focuses on the synthesis and characterization of three dimensional II-VI piezoelectric semiconductor nanowires (ZnO and CdSe nanowires). The second section (Chapters 3, 4 and 5) focuses on the applications of CdSe, ZnO and ZnO-based core/shell nanowires as gas sensor, photodetector, and multi- functional detector. A short description of each chapter is presented as below.
Chapter 2 will address the fabrication methods of three dimensional II-VI piezoelectric semiconductor nanowires (ZnO and CdSe nanowires). ZnO NW arrays have been grown on different substrates via different method and their characteristics have been investigated. In addition, well-aligned CdSe NW arrays have been synthesized via chemical vapor deposition (CVD) method, and the structure has been studied.
In Chapter 3, gas sensors based on ZnO/SnO2, ZnO/In2O3, ZnO/WO3 core/shell
heterostructures and CdSe NW arrays have been integrated. All these gas sensors can be used to detect oxidizing gas and reducing gas with/without any external power supply due to piezotronic effect. Based on these results, the piezopotential created inside ZnO and CdSe NW arrays can be
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used as self-powered energy source to develop other self-powered systems, such as self-powered photodetector and self-powered multi-functional device.
In Chapter 4, a high-performance photodetector based on ZnO/ZnSe heterostructure core/shell nanowire array will be demonstrated, and its performance and self-powered behavior will be discussed in detail. The photodetector can be used to detect the entire range of the visible spectrum, from Blue to Red excitation source, as well as UV light. Moreover, the photodetector can exhibit self-powered photodetection behavior under UV/visible light illumination.
In Chapter 5, the multi-field coupling effects among magnetic field, piezoelectricity and photoexcitation will be explored in ZnO and ZnO/Co3O4 NW arrays. The magnetic-induced
current response can be magnified by one order and two orders of magnitude due to piezo- magnetotronic effect and piezo-photo-magnetotronic effect, respectively. Moreover, ZnO/Co3O4
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Reference
(1) Ramadan, K. S.; Sameoto, D.; Evoy, S. A Review of Piezoelectric Polymers as Functional Materials for Electromechanical Transducers. Smart Mater. Struct.2014, 23 (3), 33001. (2) Jacques, C.; Pierre, C. Development, via Compression, of Electric Polarization in
Hemihedral Crystals with Inclined Faces. Bull. Soc. Minérologique Fr1880, 3, 90–93. (3) Katzir, S. Who Knew Piezoelectricity? Rutherford and Langevin on Submarine Detection
and the Invention of Sonar. Notes Rec. R. Soc.2012, 66 (2), 141–157.
(4) Uchino, K. Piezoelectric Ultrasonic Motors: Overview. Smart Mater. Struct. 1998, 7 (3), 273.
(5) Lines, M. E.; Glass, A. M. Principles and Applications of Ferroelectrics and Related Materials; Oxford [England] : Clarendon Press, 1977.
(6) Cady, W. G. Piezoelectricity : An Introduction to the Theory and Applications of
Electromechanical Phenomena in Crystals, New rev. e.; New York : Dover Publications,
1964.
(7) Jaffe, B.; Cook, W. R.; Jaffe, H. L. Piezoelectric Ceramics; London, New York, Academic Press, 1971., 1971.
(8) Marechal, P.; Levassort, F.; Holc, J.; Tran-Huu-Hue, L.-P.; Kosec, M.; Lethiecq, M. High- Frequency Transducers Based on Integrated Piezoelectric Thick Films for Medical Imaging. IEEE Trans. Ultrason. Ferroelectr. Freq. Control2006, 53 (8), 1524–1533. (9) Wang, D.; Zhang, J.; Zhu, H. Embedded Electromechanical Impedance and Strain Sensors
for Health Monitoring of a Concrete Bridge. Shock Vib.2015, 2015, 1–12.
(10) Harris, N. R.; Hill, M.; Torah, R.; Townsend, R.; Beeby, S.; White, N. M.; Ding, J. A Multilayer Thick-Film PZT Actuator for MEMs Applications. Sensors Actuators A Phys. 2006, 132 (1), 311–316.
(11) Wang, Q.-M.; Zhang, T.; Chen, Q.; Du, X.-H. Effect of DC Bias Field on the Complex Materials Coefficients of Piezoelectric Resonators. Sensors Actuators A Phys. 2003, 109
(1–2), 149–155.
(12) Wang, Z. L. Piezoelectric Nanogenerators Based on Zinc Oxide Nanowire Arrays. Science (80-. ).2006, 312 (5771), 242–246.
(13) Janotti, A.; Van de Walle, C. G. Fundamentals of Zinc Oxide as a Semiconductor. Reports Prog. Phys.2009, 72 (12), 126501.
(14) Morkoc, H.; Ozgur, U. Zinc Oxide: Fundamentals, Materials and Device Technology. In
Zinc Oxide: Fundamentals, Materials and Device Technology; Wiley-VCH Verlag GmbH & Co. KGaA: Weinheim, Germany, 2009; pp 1–76.
20
(15) Wang, Z. L.; Wu, W. Piezotronics and Piezo-Phototronics: Fundamentals and Applications. Natl. Sci. Rev.2014, 1 (1), 62–90.
(16) Zhang, Y.; Liu, Y.; Wang, Z. L. Fundamental Theory of Piezotronics. Adv. Mater. 2011,
23 (27), 3004–3013.
(17) Wang, Z. L. Piezopotential Gated Nanowire Devices: Piezotronics and Piezo- Phototronics. Nano Today2010, 5 (6), 540–552.
(18) Wang, Z. L.; Wu, W. Piezotronics and Piezo-Phototronics: Fundamentals and Applications. Natl. Sci. Rev.2014, 1 (1), 62–90.
(19) Das, S. N.; Choi, J.; Kar, J. P.; Moon, K.; Lee, T. Il; Myoung, J.-M. Junction Properties of Au/ZnO Single Nanowire Schottky Diode. Appl. Phys. Lett.2010, 96 (9), 92111.
(20) Zhou, J.; Fei, P.; Gu, Y.; Mai, W.; Gao, Y.; Yang, R.; Bao, G.; Wang, Z. L. Piezoelectric- Potential-Controlled Polarity-Reversible Schottky Diodes and Switches of ZnO Wires.
Nano Lett.2008, 8 (11), 3973–3977.
(21) Chung, K.; Wang, Z.; Costa, J. C.; Williamson, F.; Ruden, P. P.; Nathan, M. I. Barrier Height Change in GaAs Schottky Diodes Induced by Piezoelectric Effect. Appl. Phys. Lett.1991, 59 (10), 1191–1193.
(22) Yang, Q.; Liu, Y.; Pan, C.; Chen, J.; Wen, X.; Wang, Z. L. Largely Enhanced Efficiency in ZnO Nanowire/p-Polymer Hybridized Inorganic/Organic Ultraviolet Light-Emitting Diode by Piezo-Phototronic Effect. Nano Lett.2013, 13 (2), 607–613.
(23) Xue, F.; Chen, L.; Chen, J.; Liu, J.; Wang, L.; Chen, M.; Pang, Y.; Yang, X.; Gao, G.; Zhai, J.; et al. P-Type MoS 2 and N-Type ZnO Diode and Its Performance Enhancement by the Piezophototronic Effect. Adv. Mater.2016, 28 (17), 3391–3398.
(24) Han, W.; Zhou, Y.; Zhang, Y.; Chen, C.; Lin, L.; Wang, X.; Wang, S.; Wang, Z. L. Strain- Gated Piezotronic Transistors Based on Vertical Zinc Oxide Nanowires. ACS Nano 2012,
6 (5), 3760–3766.
(25) Liu, W.; Zhang, A.; Zhang, Y.; Wang, Z. L. Density Functional Studies on Wurtzite Piezotronic Transistors: Influence of Different Semiconductors and Metals on Piezoelectric Charge Distribution and Schottky Barrier. Nanotechnology 2016, 27 (20), 205204.
(26) Wang, L.; Liu, S.; Feng, X.; Xu, Q.; Bai, S.; Zhu, L.; Chen, L.; Qin, Y.; Wang, Z. L. Ultrasensitive Vertical Piezotronic Transistor Based on ZnO Twin Nanoplatelet. ACS Nano2017, 11 (5), 4859–4865.
(27) Xue, F.; Zhang, L.; Tang, W.; Zhang, C.; Du, W.; Wang, Z. L. Piezotronic Effect on ZnO Nanowire Film Based Temperature Sensor. ACS Appl. Mater. Interfaces 2014, 6 (8), 5955–5961.
(28) Yu, R.; Pan, C.; Chen, J.; Zhu, G.; Wang, Z. L. Enhanced Performance of a ZnO Nanowire-Based Self-Powered Glucose Sensor by Piezotronic Effect. Adv. Funct. Mater.
21
2013, 23 (47), 5868–5874.
(29) Fu, Y.; Nie, Y.; Zhao, Y.; Wang, P.; Xing, L.; Zhang, Y.; Xue, X. Detecting Liquefied Petroleum Gas (LPG) at Room Temperature Using ZnSnO 3 /ZnO Nanowire Piezo- Nanogenerator as Self-Powered Gas Sensor. ACS Appl. Mater. Interfaces 2015, 7 (19), 10482–10490.
(30) Zhou, Y. S.; Hinchet, R.; Yang, Y.; Ardila, G.; Songmuang, R.; Zhang, F.; Zhang, Y.; Han, W.; Pradel, K.; Mont??s, L.; et al. Nano-Newton Transverse Force Sensor Using a Vertical GaN Nanowire Based on the Piezotronic Effect. Adv. Mater. 2013, 25 (6), 883– 888.
(31) Park, S.; Kim, S.; Kheel, H.; Lee, C. Oxidizing Gas Sensing Properties of the N-ZnO/p- Co3O4 Composite Nanoparticle Network Sensor. Sensors Actuators B Chem. 2016, 222, 1193–1200.
(32) Lee, J.-H.; Lee, K. Y.; Gupta, M. K.; Kim, T. Y.; Lee, D.-Y.; Oh, J.; Ryu, C.; Yoo, W. J.; Kang, C.-Y.; Yoon, S.-J.; et al. Highly Stretchable Piezoelectric-Pyroelectric Hybrid Nanogenerator. Adv. Mater.2014, 26 (5), 765–769.
(33) Zang, W.; Wang, W.; Zhu, D.; Xing, L.; Xue, X. Humidity-Dependent Piezoelectric Output of Al–ZnO Nanowire Nanogenerator and Its Applications as a Self-Powered Active Humidity Sensor. RSC Adv.2014, 4 (99), 56211–56215.
(34) Zhu, G.; Yang, R.; Wang, S.; Wang, Z. L. Flexible High-Output Nanogenerator Based on Lateral ZnO Nanowire Array. Nano Lett.2010, 10 (8), 3151–3155.
(35) Yu, A.; Song, M.; Zhang, Y.; Kou, J.; Zhai, J.; Lin Wang, Z. A Self-Powered AC Magnetic Sensor Based on Piezoelectric Nanogenerator. Nanotechnology 2014, 25 (45), 455503.
(36) Hinchet, R.; Lee, S.; Ardila, G.; Montès, L.; Mouis, M.; Wang, Z. L. Performance Optimization of Vertical Nanowire-Based Piezoelectric Nanogenerators. Adv. Funct. Mater.2014, 24 (7), 971–977.
(37) Wang, Z. L. Towards Self-Powered Nanosystems: From Nanogenerators to Nanopiezotronics. Adv. Funct. Mater.2008, 18 (22), 3553–3567.
(38) Wang, Z. L. Piezopotential Gated Nanowire Devices: Piezotronics and Piezo- Phototronics. Nano Today2010, 5 (6), 540–552.
(39) Price, P. W.; Beckerman, a P.; Fretwell, S. D.; Arruda, J.; Pimm, S. L.; Carpenter, S. R.; Cardinale, B. J.; Martinez, N. D.; Morris, R. J.; Godfray, H. C. J.; et al. Biomechanical Energy Harvesting : Sci. Rep.2008, 319 (February), 807–810.
(40) Ottman, G. K.; Hofmann, H. F.; Bhatt, A. C.; Lesieutre, G. A. Adaptive Piezoelectric Energy Harvesting Circuit for Wireless Remote Power Supply. IEEE Trans. Power Electron.2002, 17 (5), 669–676.
22
Backpack Instrumented with Piezoelectric Shoulder Straps. Smart Mater. Struct.2007, 16
(5), 1810–1820.
(42) Kumar, P.; Dwivedy, S. K.; Kumari, P. Dynamic Analysis of Piezoelectric Based Energy Harvester under Periodic Excitation. Procedia Eng.2016, 144, 635–644.
(43) Paradiso, J. A.; Starner, T. Energy Scavenging for Mobile and Wireless Electronics. IEEE Pervasive Comput.2005, 4 (1), 18–27.
(44) Yang, Q.; Guo, X.; Wang, W.; Zhang, Y.; Xu, S.; Lien, D. H.; Wang, Z. L. Enhancing Sensitivity of a Single ZnO Micro-/Nanowire Photodetector by Piezo-Phototronic Effect.
ACS Nano2010, 4 (10), 6285–6291.
(45) Wu, W.; Pan, C.; Zhang, Y.; Wen, X.; Wang, Z. L. Piezotronics and Piezo-Phototronics – From Single Nanodevices to Array of Devices and Then to Integrated Functional System.
Nano Today2013, 8 (6), 619–642.
(46) Javadi, M.; Darbari, S.; Abdi, Y.; Ghasemi, F. Realization of a Piezophototronic Device Based on Reduced Graphene Oxide/MoS2 Heterostructure. IEEE Electron Device Lett. 2016, 37 (5), 677–680.
(47) Wen, X.; Wu, W.; Wang, Z. L. Effective Piezo-Phototronic Enhancement of Solar Cell Performance by Tuning Material Properties. Nano Energy2013, 2 (6), 1093–1100.
(48) Hu, G.; Guo, W.; Yang, X.; Zhou, R.; Pan, C.; Wang, Z. L. Enhanced Performances of Flexible ZnO/perovskite Solar Cells by Piezo-Phototronics Effect. Nano Energy2016, 23, 27–33.
(49) Wong, M.; Chen, L.; Tsang, M.; Zhang, Y.; Hao, J. Magnetic-Induced Luminescence from Flexible Composite Laminates by Coupling Magnetic Field to Piezophotonic Effect.
Adv. Mater.2015, 27, 4488–4495.
(50) Pan, C.; Dong, L.; Zhu, G.; Niu, S.; Yu, R.; Yang, Q.; Liu, Y.; Wang, Z. L. High- Resolution Electroluminescent Imaging of Pressure Distribution Using a Piezoelectric Nanowire LED Array. Nat. Photonics2013, 7 (9), 752–758.
(51) Shi, J.; Starr, M. B.; Xiang, H.; Hara, Y.; Anderson, M. A.; Seo, J.; Ma, Z.; Wang, X. Interface Engineering by Piezoelectric Potential in ZnO-Based Photoelectrochemical Anode. Nano Lett.2011, 11 (12), 5587–5593.
(52) Chen, T.; Young, S.; Chang, S.; Hsiao, C.; Hsu, Y. Bending Effects of ZnO Nanorod Metal–semiconductor–metal Photodetectors on Flexible Polyimide Substrate. Nanoscale Res. Lett.2012, 7 (1), 214–219.
(53) Zhang, F.; Niu, S.; Guo, W.; Zhu, G.; Liu, Y.; Zhang, X.; Wang, Z. L. Piezo-Phototronic Effect Enhanced Visible/UV Photodetector of a Carbon-Fiber/ZnO-CdS Double-Shell Microwire. ACS Nano2013, 7 (5), 4537–4544.
(54) Yang, Q.; Wu, Y.; Liu, Y.; Pan, C.; Wang, Z. L. Features of the Piezo-Phototronic Effect on Optoelectronic Devices Based on Wurtzite Semiconductor Nanowires. Phys. Chem.
23
Chem. Phys.2014, 16 (7), 2790–2800.
(55) Hu, B. Y. and Y. Q. and H. Z. and Y. L. and Y. Z. and D. Y. and L. Improved Photoresponse Performance of a Self-Powered Si/ZnO Heterojunction Ultraviolet and Visible Photodetector by the Piezo-Phototronic Effect. Semicond. Sci. Technol. 2017, 32
(6), 64002.
(56) Yang, Q.; Wang, W.; Xu, S.; Wang, Z. L. Enhancing Light Emission of ZnO Microwire- Based Diodes by Piezo-Phototronic Effect. Nano Lett.2011, 11 (9), 4012–4017.
(57) Pan, C.; Niu, S.; Ding, Y.; Dong, L.; Yu, R.; Liu, Y.; Zhu, G.; Wang, Z. L. Enhanced Cu 2 S/CdS Coaxial Nanowire Solar Cells by Piezo-Phototronic Effect. Nano Lett.2012, 12 (6), 3302–3307.
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