博碩士論文 102282001 詳細資訊



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姓名 林侑鋌(Yu-Ting Lin)  查詢紙本館藏   畢業系所 物理學系
論文名稱
(Nanoelectronics and temperature dependent transport properties of two-dimensional materials)
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摘要(中) 二碲化鎢(WTe2)是一種新穎且具有前瞻性的二維材料。它的晶格結構具有高異相性且已經被證實在低溫的環境下(低於10 K)有著超巨大磁阻(extremely large magnetoresistance, XMR)。近來，雙層與多層的WTe2單晶晶體在室溫(300 K)的環境下，已被證實有著顯著的鐵電性(Ferroelectricity, FE)。此外，單層的WTe2單晶薄膜在100 K的環境下，也被發現存在著量子自旋霍爾效應(Quantum spin Hall effect, QSHE)。這些發現強烈地指出，WTe2在下一個世代的電子元件與自旋電子元件中有著巨大的潛力。因此，為了能夠整合它的磁傳輸性質與上述新穎的特性，研究其磁阻與溫度的關係與在高溫環境下實現大的磁阻 (large MR) 是必要的。然而，迄今為止大部分WTe2相關的研究主要是在機械剝離 (mechanical exfoliation) 的樣品中被實現，且溫度相關的磁傳輸性質的研究仍然非常稀少。在這個實驗中，藉由化學氣象沉積法(chemical vapor deposition, CVD)，高品質且厚度可調控的WTe2單晶晶體被成功地合成。在高溫環境下(高於80 K)，大的磁阻被首次實現於合成的WTe2單晶晶體中。此外，藉由調控材料中的載子濃度，其磁阻可以被進一步地調控與增強。
摘要(英) Tungsten ditelluride (WTe2) is a kind of low symmetry two-dimensional (2D) materials and exhibits extremely large magnetoresistance (XMR) below 10K. Recently, understanding of novel properties in the materials is highlighted to induce unique properties at elevated temperature. Ferroelectricity (FE) of the bilayer WTe2 is experimentally observed at 300K and quantum spin Hall effect (QSHE) of the monolayer WTe2 is demonstrated at 100K, suggesting diverse possibilities for next generation electronics and spintronics. Hence, study of the temperature dependent magnetoresistance (MR) of the WTe2 is essential for real applications and deep insights. However, most reported studies on fundamental issues are mainly achieved with exfoliated WTe2 for reduced disorders and hexagonal boron nitride (h-BN) encapsulation for ideal interfaces. In this thesis, the enhanced performances of the synthesized WTe2 single crystals are demonstrated. Tunable thickness and high crystallinity of the WTe2 are achieved using KCl-assisted chemical vapor deposition (CVD). A large MR of the WTe2 above 80K is experimentally realized for the first time, and the MR is engineerable by tuning the carrier configuration.
關鍵字(中) ★ 二維材料
★ 過渡金屬硫族化合物
★ 電子傳輸性質
★ 磁傳輸性質		 關鍵字(英) ★ two dimensional materials
★ transition metal dichalcogenides
★ electronic transport
★ magneto-transport
論文目次 1 Introduction 1
2 Background 5
2.1 Atomic structure of the WTe2 5
2.2 Band structure of the WTe2 8
2.3 Extremely large and non-saturating magnetoresistance 10
2.4 Negative magnetoresistance 16
2.5 Temperature-induced Lifshitz transition 19
2.6 Quantum spin Hall effect 22
2.7 Ferroelectricity 27
2.8 Weak antilocalization 29
2.9 Motivation and challenges 34

3 Experimental procedure and methods 36
3.1 Material synthesis 37
3.2 Material characterization 38
3.2.1 Surface morphology 38
3.2.2 Optical characterization 39
3.2.3 Chemical configuration 39
3.3 Device fabrication 40
3.4 Electronic transport and magneto-transport measurements 42

4 Results and discussion 45
4.1 Synthesis of WTe2 flakes with tunable thickness 45
4.2 Characterization of the as-grown few-layer WTe2 flakes 47
4.2.1 Surface morphology 47
4.2.2 Optical characterization 48
4.2.3 Chemical configuration 50
4.3 Electronic transport properties of the few-layer WTe2 flakes 51
4.3.1 Ohmic contact confirmation 51
4.3.2 Thickness dependent resistivity and residual resistivity ratio 53
4.4 Magneto-transport properties of the few-layer WTe2 flakes 55
4.4.1 Temperature dependent magneto-transport properties 55
4.4.2 Field dependent magneto-transport properties 56
4.4.3 Thickness dependent magneto-transport properties 58

4.5 Benchmarks of the temperature-dependent MR of the WTe2 samples 62
4.6 The effect of doping on the magneto-transport properties of the few-layer WTe2 flakes 65
4.6.1 Doping strategy 65
4.6.2 Temperature dependent magneto-transport properties 67
4.6.3 Field dependent magneto-transport properties 68

5 Conclusions 70
6 References 74
參考文獻 1. M. N. Baibich et al., Giant magnetoresistance of (001) Fe/(001) Cr magnetic superlattices. Phys. Rev. Lett. 61, 2472 (1988).
2. G. Binasch, P. Grünberg, F. Saurenbach, W. J. P. r. B. Zinn, Enhanced magnetoresistance in layered magnetic structures with antiferromagnetic interlayer exchange. Phys. Rev. B 39, 4828 (1989).
3. M. N. Ali et al., Large, non-saturating magnetoresistance in WTe2. Nature 514, 205-208 (2014).
4. F. F. Tafti, Q. D. Gibson, S. K. Kushwaha, N. Haldolaarachchige, R. J. Cava, Resistivity plateau and extreme magnetoresistance in LaSb. Nat. Phys. 12, 272-277 (2016).
5. C. Shekhar et al., Extremely large magnetoresistance and ultrahigh mobility in the topological Weyl semimetal candidate NbP. Nat. Phys. 11, 645-649 (2015).
6. T. Liang et al., Ultrahigh mobility and giant magnetoresistance in the Dirac semimetal Cd3As2. Nat. Mater. 14, 280-284 (2015).
7. Y. J. Wang et al., Gate-tunable negative longitudinal magnetoresistance in the predicted type-II Weyl semimetal WTe2. Nat. Commun. 7, 13142 (2016).
8. P. Li et al., Evidence for topological type-II Weyl semimetal WTe2. Nat. Commun. 8, 2150 (2017).
9. V. Fatemi et al., Electrically tunable low-density superconductivity in a monolayer topological insulator. Science 362, 926-929 (2018).
10. Q. Ma et al., Observation of the nonlinear Hall effect under time-reversal-symmetric conditions. Nature 565, 337-342 (2019).
11. S. Y. Xu et al., Electrically switchable Berry curvature dipole in the monolayer topological insulator WTe2. Nat. Phys. 14, 900-906 (2018).
12. Z. Y. Fei et al., Edge conduction in monolayer WTe2. Nat. Phys. 13, 677-682 (2017).
13. S. F. Wu et al., Observation of the quantum spin Hall effect up to 100 kelvin in a monolayer crystal. Science 359, 76-79 (2018).
14. Y. M. Shi et al., Imaging quantum spin Hall edges in monolayer WTe2. Sci. Adv. 5, eaat8799 (2019).
15. Z. Y. Fei et al., Ferroelectric switching of a two-dimensional metal. Nature 560, 336-339 (2018).
16. P. Sharma et al., A room-temperature ferroelectric semimetal. Sci. Adv. 5, eaax5080 (2019).
17. D. MacNeill et al., Control of spin-orbit torques through crystal symmetry in WTe2/ferromagnet bilayers. Nat. Phys. 13, 300-305 (2017).
18. P. Li et al., Spin-momentum locking and spin-orbit torques in magnetic nano-heterojunctions composed of Weyl semimetal WTe2. Nat. Commun. 9, 3990 (2018).
19. Y. J. Wang et al., Direct Evidence for Charge Compensation-Induced Large Magnetoresistance in Thin WTe2. Nano Lett. 19, 3969-3975 (2019).
20. Y. Zhou et al., Direct Synthesis of Large-Scale WTe2 Thin Films with Low Thermal Conductivity. Adv. Funct. Mater. 27, 1605928 (2017).
21. J. Kwak et al., Single-Crystalline Nanobelts Composed of Transition Metal Ditellurides. Adv. Mater. 30, 1707260 (2018).
22. J. D. Zhou et al., Large-Area and High-Quality 2D Transition Metal Telluride. Adv. Mater. 29, 1603471 (2017).
23. E. Z. Zhang et al., Tunable Positive to Negative Magnetoresistance in Atomically Thin WTe2. Nano Lett. 17, 878-885 (2017).
24. C. H. Naylor et al., Large-area synthesis of high-quality monolayer 1T′-WTe2 flakes. 2D Mater. 4, 021008 (2017).
25. Y. Wu et al., Temperature-Induced Lifshitz Transition in WTe2. Phys. Rev. Lett. 115, 166602 (2015).
26. R. Kappera et al., Phase-engineered low-resistance contacts for ultrathin MoS 2 transistors. Nat. Mater. 13, 1128-1134 (2014).
27. H. Huang et al., Metallic 1T phase MoS2 nanosheets for high-performance thermoelectric energy harvesting. Nano Energy 26, 172-179 (2016).
28. W. Zhao et al., Metastable MoS2: Crystal Structure, Electronic Band Structure, Synthetic Approach and Intriguing Physical Properties. Chem.-Eur. J. 24, 15942-15954 (2018).
29. E. J. Sie et al., An ultrafast symmetry switch in a Weyl semimetal. Nature 565, 61-66 (2019).
30. S. Y. Xu et al., Discovery of a Weyl fermion semimetal and topological Fermi arcs. Science 349, 613-617 (2015).
31. A. A. Soluyanov et al., Type-ii weyl semimetals. Nature 527, 495-498 (2015).
32. S. Jin et al., Thousandfold Change in Resistivity in Magnetoresistive La-Ca-Mn-O Films. Science 264, 413-415 (1994).
33. R. Vonhelmolt, J. Wecker, B. Holzapfel, L. Schultz, K. Samwer, Giant Negative Magnetoresistance in Perovskitelike La2/3ba1/3mnox Ferromagnetic-Films. Phys. Rev. Lett. 71, 2331-2333 (1993).
34. P. Alers, R. J. P. R. Webber, The magnetoresistance of bismuth crystals at low temperatures. Phys. Rev. 91, 1060 (1953).
35. F. Yang et al., Large magnetoresistance of electrodeposited single-crystal bismuth thin films. Science 284, 1335-1337 (1999).
36. Y. Wang et al., Origin of the turn-on temperature behavior in WTe2. Phys. Rev. B 92, 180402 (2015).
37. L. Wang et al., Tuning magnetotransport in a compensated semimetal at the atomic scale. Nat. Commun. 6, 8892 (2015).
38. D. Fu et al., Tuning the electrical transport of type II Weyl semimetal WTe 2 nanodevices by Ga+ ion implantation. Sci. Rep. 7, 12688 (2017).
39. D. Fu et al., Tuning the electrical transport of type II Weyl semimetal WTe2 nanodevices by Mo doping. Nanotech. 29, 135705 (2018).
40. X. Luo et al., Magnetoresistance and Hall resistivity of semimetal WTe2 ultrathin flakes. Nanotech. 28, 145704 (2017).
41. Y. K. Luo et al., Hall effect in the extremely large magnetoresistance semimetal WTe2. Appl. Phys. Lett. 107, 182411 (2015).
42. V. Fatemi et al., Magnetoresistance and quantum oscillations of an electrostatically tuned semimetal-to-metal transition in ultrathin WTe2. Phys. Rev. B 95, 041410(R) (2017).
43. X. C. Huang et al., Observation of the Chiral-Anomaly-Induced Negative Magnetoresistance in 3D Weyl Semimetal TaAs. Phys. Rev. X 5, 031023 (2015).
44. C. Liu et al., Evidence for a Lifshitz transition in electron-doped iron arsenic superconductors at the onset of superconductivity. Nat. Phys. 6, 419-423 (2010).
45. X. C. Pan et al., Pressure-driven dome-shaped superconductivity and electronic structural evolution in tungsten ditelluride. Nat. Commun. 6, 7805 (2015).
46. S. J. Tang et al., Quantum spin Hall state in monolayer 1T ′-WTe2. Nat. Phys. 13, 683-687 (2017).
47. J. J. P. r. Valasek, Piezo-electric and allied phenomena in Rochelle salt. Phys. Rev. 17, 475 (1921).
48. H. M. Yau et al., Low-field Switching Four-state Nonvolatile Memory Based on Multiferroic Tunnel Junctions. Sci. Rep. 5, 12826 (2015).
49. T. Choi, S. Lee, Y. J. Choi, V. Kiryukhin, S.-W. J. S. Cheong, Switchable ferroelectric diode and photovoltaic effect in BiFeO3. Science 324, 63-66 (2009).
50. J. Haeni et al., Room-temperature ferroelectricity in strained SrTiO3. Nature 430, 758-761 (2004).
51. S. Wan et al., Room-temperature ferroelectricity and a switchable diode effect in two-dimensional α-In2Se3 thin layers. Nanoscale 10, 14885-14892 (2018).
52. Y. Zhou et al., Out-of-plane piezoelectricity and ferroelectricity in layered α-In2Se3 nanoflakes. Nano Lett. 17, 5508-5513 (2017).
53. W. Ding et al., Prediction of intrinsic two-dimensional ferroelectrics in In 2 Se 3 and other III2-VI3 van der Waals materials. Nat. Commun. 8, 14956 (2017).
54. H.-Z. Lu and S.-Q. Shen, Weak localization and weak anti-localization in topological insulators. in Spintronics Vii. (International Society for Optics and Photonics), 9167, p. 91672E (2014).
55. F. Tikhonenko, D. Horsell, R. Gorbachev, A. J. P. r. l. Savchenko, Weak localization in graphene flakes. Phys. Rev. Lett. 100, 056802 (2008).
56. C. D. Cress et al., Nitrogen-doped graphene and twisted bilayer graphene via hyperthermal ion implantation with depth control. ACS Nano 10, 3714-3722 (2016).
57. Y. Du, A. T. Neal, H. Zhou, D. Y. J. D. M. Peide, Weak localization in few-layer black phosphorus. 2D Mater. 3, 024003 (2016).
58. E. Amaladass, A. Chatterjee, S. Sharma, A. Mani, S. J. M. R. E. Shivaprasad, Weak localization and electron–electron interaction in GaN nanowalls. Mater. Res. Express 4, 095014 (2017).
59. B. Zhao et al., Weak antilocalization in Cd3As2 thin films. Sci. Rep. 6, 22377 (2016).
60. C. H. Naylor et al., Monolayer single-crystal 1T′-MoTe2 grown by chemical vapor deposition exhibits weak antilocalization effect. Nano Lett. 16, 4297-4304 (2016).
61. J. Zeng et al., Gate-tunable weak antilocalization in a few-layer InSe. Phys. Rev. B 98, 125414 (2018).
62. H. Liu et al., Quasi-2D Transport and Weak Antilocalization Effect in Few-Layered VSe2. Nano Lett. 19, 4551-4559 (2019).
63. W. L. Liu et al., Effect of aging-induced disorder on the quantum transport properties of few-layer WTe2. 2D Mater. 4, 011011 (2017).
64. J. M. Woods et al., Suppression of magnetoresistance in thin WTe2 flakes by surface oxidation. ACS Appl. Mater. Interfaces 9, 23175-23180 (2017).
65. M. Gao et al., Tuning the transport behavior of centimeter-scale WTe2 ultrathin films fabricated by pulsed laser deposition. Appl. Phys. Lett. 111, 031906 (2017).
66. L. A. Walsh et al., WTe2 thin films grown by beam-interrupted molecular beam epitaxy. 2D Mater. 4, 025044 (2017).
67. J. Li, S. Cheng, Z. Liu, W. Zhang, H. J. T. J. o. P. C. C. Chang, Centimeter-Scale, Large-Area, Few-Layer 1T′-WTe2 Films by Chemical Vapor Deposition and Its Long-Term Stability in Ambient Condition. J. Phys. Chem. C 122, 7005-7012 (2018).
68. Q. J. Song et al., The In-Plane Anisotropy of WTe2 Investigated by Angle-Dependent and Polarized Raman Spectroscopy. Sci. Rep. 6, 29254 (2016).
69. F. X. Xiang et al., Thickness-dependent electronic structure in WTe2 thin films. Phys Rev B 98, (2018).
70. X. Liu et al., Gate tunable magneto-resistance of ultra-thin WTe2 devices. 2D Mater. 4, 021018 (2017).
71. S. H. H. Shokouh et al., High-Performance, Air-Stable, Top-Gate, p-Channel WSe2 Field-Effect Transistor with Fluoropolymer Buffer Layer. Adv. Funct. Mater. 25, 7208-7214 (2015).
72. B. Liu et al., Engineering Bandgaps of Monolayer MoS2 and WS2 on Fluoropolymer Substrates by Electrostatically Tuned Many-Body Effects. Adv. Mater. 28, 6457-6464 (2016).
指導教授 陳永富 李奕賢(Yung‐Fu Chen Yi-Hsien Lee) 審核日期 2020-1-21
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