1. Nano Structures and Dynamics Lab., MSE, NTHU Self-Assembled Nanostructures Mediated by Gold Particles Lih J. Chen Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan

2. Nano Structures and Dynamics Lab., MSE, NTHU Nano = “dwarf” in Greek

3. Nano Structures and Dynamics Lab., MSE, NTHU

5. J. Heath, L-09, School on Nanomechanics, Hawaii (2002).

6. Nano Structures and Dynamics Lab., MSE, NTHU Nature, 419, 553 (2002).

7. Nano Structures and Dynamics Lab., MSE, NTHU 1D nanostructures to provide a good system to investigate the dependence of electrical and thermal transport or mechanical properties on dimensionality and size reduction to play an important role as both interconnects and functional units in fabricating electronic, optoelectronic, electrochemical, and electromechanical devices with nanoscale dimensions

8. Nano Structures and Dynamics Lab., MSE, NTHU

9. micro- (cells) and nanostructure (wax crystals)

10. Nano Structures and Dynamics Lab., MSE, NTHU Opal ( 蛋白石 ) 與其奈米結構

11. Nano Structures and Dynamics Lab., MSE, NTHU 蝴蝶翅膀與其奈米結構

12. Nano Structures and Dynamics Lab., MSE, NTHU  Small-sized Au catalysis has attracted increasing interest because of the discovery of extraordinary catalytic activity and specificity.  Au nanoparticles consisting of metal inner-core and organic outer-shell can be acquired as the nanostructured catalysts from size controllability, monodispersity, processibility, and aggregation resistivity.  Self-assembled honeycomb networks of Au nanoparticles show promise as the regular patterns for the growth of various nanowires without complex lithography. Introduction

13. Nano Structures and Dynamics Lab., MSE, NTHU Two-phase Method (Au@TOAB) Stirrer plate Phase-transfer reagents (C 8 H 7 ) 4 NBr Reduction reagent (NaBH 4 ) HAuCl 4 ·3H 2 O (aq.) Stirring rod

14. Nano Structures and Dynamics Lab., MSE, NTHU Au@TOAB R= C 8 H 17 R’= C 12 H 25 Au@TOAB-DT N R R R R Br Au N R R R R Br N R R R R N R R R R N R R R R N R R R R N R R R R N R R R R Au S R’ S S S S S S S S S S S S S S S TOAB desorption DT adsorption Displacement Reaction of Outer-Shells

15. Nano Structures and Dynamics Lab., MSE, NTHU Displacement Reaction of Outer-Shells TOAB desorption DT adsorption Au@TOAB Au@TOAB-DT

16. Nano Structures and Dynamics Lab., MSE, NTHU Au@TOAB-DT Frequency Diameter (nm) std dev. 0.27nm

17. Nano Structures and Dynamics Lab., MSE, NTHU Drying Pattern Si substrate/Cu/Al Controlled temperature Si substrate/Cu/Al Controlled temperature

18. Nano Structures and Dynamics Lab., MSE, NTHU Self-assembled honeycomb networks (as-cast)

19. Nano Structures and Dynamics Lab., MSE, NTHU 800 ℃ Back

20. Nano Structures and Dynamics Lab., MSE, NTHU 400-1000-1000 0 C, 30 min

21. Nano Structures and Dynamics Lab., MSE, NTHU 400-1000 0 C, 30 min P.Y. Su et al. Appl. Phys. Lett. 84, 3480 (2004).

22. Nano Structures and Dynamics Lab., MSE, NTHU 1100 0 C, 30 min

23. Nano Structures and Dynamics Lab., MSE, NTHU

25. 1100 ℃ Back

26. Nano Structures and Dynamics Lab., MSE, NTHU Nano Structures and Dynamics Lab MSE NTHU 950 ℃ -60 min1050 ℃ -60 min1000 ℃ -75 min 1080 ℃ -60 min

27. Nano Structures and Dynamics Lab., MSE, NTHU

28. 氧化矽奈米線與其對應陰極發光圖

29. Nano Structures and Dynamics Lab., MSE, NTHU

31. at % O 70.33 Si 24.12 Au 5.55 at % O 39.94 Si 33.36 Au 26.7 EDS Analysis

32. Nano Structures and Dynamics Lab., MSE, NTHU

34. TEM observation 100 nm 1 µm 100 nm Si substrate 100-nm-thick oxide

35. Nano Structures and Dynamics Lab., MSE, NTHU 100 nm O Si Cu O Si Cu Au EDS analysis

36. Nano Structures and Dynamics Lab., MSE, NTHU As cast 200 - 950 ℃ 1000 ℃ 1100 ℃

37. Nano Structures and Dynamics Lab., MSE, NTHU thin oxide ~10 nm Au-O compound oxide ~10 nm Si

38. Nano Structures and Dynamics Lab., MSE, NTHU thick oxide ~100 nm Au-O compound Si SiO 2 oxide ~100 nm

39. Nano Structures and Dynamics Lab., MSE, NTHU SiO x decomposed Si Au Ⅰ 100-nm-thick thermal oxide layer Au-Si-O liquid alloy Si Ⅱ Ⅲ a. VLS growth mechanism Vapor source 1. 2. Si(s) + SiO 2 (s) 2SiO x (g) SiO x (L) SiO x (g) b. Oxide-assisted growth mechanism SiO x vapor SiO x wire Feature: high-purity nanowires without the need of a metal catalyst Adv. Mater. 15, 635 (2003) Si flower-like structure

40. Nano Structures and Dynamics Lab., MSE, NTHU Si Nano Lett., 3, 1317 (2003) ： Au particle ： ZnO nanorod

41. Nano Structures and Dynamics Lab., MSE, NTHU P. Yang et al. J. Am. Chem. Soc. 125, 4728 (2003) Dynamics and Nanostructures Lab. ZnO Nanolasers: What on Earth? Z. L. Wang et al. Nano Lett. 2004, 4, 423. ★ ZnO Dendritic Array ★ ZnO nonorods Power-dependent PL spectra Angle-dependent PL spectra substrate Excitation light Light emission ZnO nanorods

42. Nano Structures and Dynamics Lab., MSE, NTHU Growth of ZnO nanowires

43. Nano Structures and Dynamics Lab., MSE, NTHU ★ 1D ZnO arrays were synthesized at 800 ℃ -1100 ℃ for 90 min.

44. Nano Structures and Dynamics Lab., MSE, NTHU PL Spectrum of ZnO Nanolasers 386 nm Annealing Temperature ( ℃ ) PL Intensity (arb. unit)

45. Nano Structures and Dynamics Lab., MSE, NTHU ★ Patterned Au nanodots by AFM ★ ★ Substrate: ZnO/Si or Al 2 O 3 substrate

46. Nano Structures and Dynamics Lab., MSE, NTHU Patterned ZnO Lasers by SPL ★ working pressure: 2.7 torr

47. Nano Structures and Dynamics Lab., MSE, NTHU ZnS Nanorods

48. Nano Structures and Dynamics Lab., MSE, NTHU Au/Sapphire

49. Nano Structures and Dynamics Lab., MSE, NTHU Si/Au/Sapphire

50. Nano Structures and Dynamics Lab., MSE, NTHU Si/Au/Sapphire

51. Nano Structures and Dynamics Lab., MSE, NTHU Si/Au/Sapphire

52. Nano Structures and Dynamics Lab., MSE, NTHU Si/Au/Sapphire

53. Nano Structures and Dynamics Lab., MSE, NTHU Vapor transport process:self-organized Au particles on Al 2 O 3 substrate - 910 0 C, Si source- 1200 0 C, Ar carrier gas 50 sccm, 2hr+3hr+5hr Vapor transport process: self-organized Au particles on Al 2 O 3 substrate - 910 0 C, Si source- 1200 0 C, Ar carrier gas 50 sccm, 2hr+3hr+5hr Al 2 O 3 Zone axis [1,-1,0] [0,0,6] [1,1,1] [1,-1,1] [0,2,0] Au Zone axis [1,0,-1] Al 2 O 3 Zone axis [1,-1,0] [1,1,1] [0,0,6] Au (1,1,1) // Al 2 O 3 (0,0,6) Au (0,2,0) d = 0.204 nm Al 2 O 3 (1,1,3) d = 0.208 nm Epitaxy ???

54. Nano Structures and Dynamics Lab., MSE, NTHU 1 2 3 Vapor transport process:self-organized Au particles on Al 2 O 3 substrate - 910 0 C, Si source- 1200 0 C, Ar carrier gas 50 sccm, 2hr+3hr+5hr Vapor transport process: self-organized Au particles on Al 2 O 3 substrate - 910 0 C, Si source- 1200 0 C, Ar carrier gas 50 sccm, 2hr+3hr+5hr

55. Nano Structures and Dynamics Lab., MSE, NTHU 1 2 3

56. 100 nm

57. Nano Structures and Dynamics Lab., MSE, NTHU 50 nm

58. Nano Structures and Dynamics Lab., MSE, NTHU Vapor transport process:self-organized Au particles on Si (111) Vapor transport process: self-organized Au particles on Si (111) substrate - 910 0 C, Si source- 1200 0 C, 2 hr, Ar carrier gas 50 sccm

59. Nano Structures and Dynamics Lab., MSE, NTHU (a)(b) Si source, 900 0 C

60. Nano Structures and Dynamics Lab., MSE, NTHU Fig. 1 (a) Model structures of Au nanocluster (with 68 Au atoms) after 900 0 C, 1601 3fs-time steps (4.8ps) simulated annealing. (b) Displacement curves of Au atoms during the 900 0 C simulated annealing. The surface diffusion speed can be as high as 100 m/sec at 900 0 C. Simulation results : the initial model structure of Au fcc cluster

61. Nano Structures and Dynamics Lab., MSE, NTHU Fig. 2 Atomic structures of four SiO molecules initially absorbed on the Au nanocluster (with 68 Au atoms) surface (a) and after 1001 time steps (3ps) simulation (b). (c) Displacement curves of Au (black), and Si-O (color) atoms during the 900 0 C simulated annealing. Simulation result : the interaction of SiO vapor with Au particle None of the SiO molecules was found to diffuse into Au cluster. The SiO molecules exhibit higher surface diffusion speed than Au atom. After absorbing the SiO molecules, the surface diffusion speed of Au atom decrease.

62. Nano Structures and Dynamics Lab., MSE, NTHU Fig. 3 Atomic structures of four Si atoms initially absorbed on the Au nanocluster (with 68 Au atoms) surface (a) and after 1001 time steps (3ps) simulation (b). (c) Displacement curves of Au (black), Si (color) atoms during the 900 0 C simulated annealing. Simulation result : the interaction of Si vapor with Au particle Si atoms absorbed onto the Au surface would intermix with Au atoms.

63. Nano Structures and Dynamics Lab., MSE, NTHU Self-organized Ag particle network

64. Nano Structures and Dynamics Lab., MSE, NTHU

66. TFP + water, rapid evaporation

67. Nano Structures and Dynamics Lab., MSE, NTHU Nanoparticle Network

68. Nano Structures and Dynamics Lab., MSE, NTHU Thickness Dependence Morphology FESEM images with the same magnifications of different spin-coated speed shown as follows (a) 1000rpm (b) 2200rpm (c) 3100rpm (d) 3800rpm (e) 4300rpm (f) 5200rpm (g) 6400rpm (h) 7100rpm (g) 8300rpm, respectively 100n m (a) (b) (c) (d)(e)(f) (g)(h)(i) Self-Assemble Diblock Copolymer 18n m 36n m 1μm1μm Two fabrication methods: Diblock copolymer& nanosphere

69. Nano Structures and Dynamics Lab., MSE, NTHU 1μm1μm 1μm1μm Polystyrene Nanospheres 1μm1μm 1μm1μm 10μm 1μm1μm Evaporation Deposition Sputtering Coatings

70. Nano Structures and Dynamics Lab., MSE, NTHU 10μm 1μm1μm Size-Tunable Platinum Nanoparticles 100nm As-sputtered ImageAs-annealed Image

71. Nano Structures and Dynamics Lab., MSE, NTHU 1μm1μm 100nm Low and high magnification SEM images of nickel disilicide array formed by electron beam evaporation after annealing the Ni at 900 ℃. Chemical oxide Another approach: ion implantation and solid phase epitaxy Si oxide Ge ion SPE and oxide removal Periodic nanometer scale stress filed template

72. Nano Structures and Dynamics Lab., MSE, NTHU Growth of nanostructures on Si and Si 1-x Ge x /(001)Si heterostructures

73. Nano Structures and Dynamics Lab., MSE, NTHU Growth of Si-Ge oxide nanowires

74. Nano Structures and Dynamics Lab., MSE, NTHU Au particles on Si 0.8 Ge 0.2, 1140 0 C, 30 min

75. Nano Structures and Dynamics Lab., MSE, NTHU Wavelength (nm) PL Intensity (arb. unit) 470 nm 415 nm Si and Si 1-x Ge x substrates annealed 1140 ℃ for 1h PL measurement of Si and Si 1-x Ge x oxide nanostructures

76. Nano Structures and Dynamics Lab., MSE, NTHU PL Spectra of SiGeONWs at Different Annealing Temperature Annealing Temperature ( ℃ ) PL Peak Wavelength ( nm )PL Peak intensity ( a.u. ) Annealing temperature↑, Density of NWs↑, PL peak intensity↑. PL peak position towards the longer wavelength slightly.

77. Nano Structures and Dynamics Lab., MSE, NTHU Conclusions 1. Self-assembled growth of hexagonal Au or Ag particle networks on a variety of substrates (Si, SiO x, Si-Ge, Si 3 N 4, Al 2 O 3, MgO) has been achieved 2. The presence of an oxide layer at the Au/Si interface stabilizes the Au particles at the intersections at a temperature as high as 1000 ℃.

78. Nano Structures and Dynamics Lab., MSE, NTHU Conclusions 3. The cell and particle size can be adjusted from 200 nm-12  m and 20-400 nm, respectively 4. A wealth of novel nanostructures (SiO x, Si and ZnO nanowires, Cu nanoparticles) can be grown on the templates

79. Nano Structures and Dynamics Lab., MSE, NTHU Conclusions 5. The network provides a convenient template for the preparation of other functionalized materials (SH- group) for a variety of applications 6. The template with its distinct structure shall permit the monitoring of changes occurred on individual particles, which may leads applications such as molecular sensing 7. The growth mechanisms of nanostructures can be elucidated by in-situ TEM

80. Nano Structures and Dynamics Lab., MSE, NTHU Acknowledgments P.Y. Su, J.C. Hu, J.H. He, T.F. Chiang, J.H. Wang (MSE, NTHU) J.M. Liang (NDL, NSC) M. Huang, T.C. Kwo (Chem, NTHU) S.L. Cheng (CMS, NCU) NSC, MoE