1. (Field Emitters, LEDs and Energy Devices)
Well patterned three-dimensional (3D) nano-structure arrays for device applications.
(Field Emitters, LEDs and Energy Devices)
Dr. GHULAM NABI
Assistant Professor
Department of Physics, UoG, Pakistan
Institute of Physics, TU-Ilmenau, Germany
ISS-2017 (13-17 March) 1

2. Contents * 3D Nanostructures-Aims ** Synthesis Techniques
*** Applications 2

3. 3D Nano-structure arrays for devices
Three-dimensional (3D) nano-structure materials are of great interest due to their potential applications in optoelectronic, Field Emitters and energy devices
What are 3D nano-structures?
1D nano-structure units combined in a regular pattern on large scale are called 3D nano-structures.
Basic Unit for 3D nano-structures are 1D nano-wires, 1D nano-rods, 1D nano-tubes or 1D core shell nanostructures etc.
3D nano-tubes structures
3D nano-rod
structures 3

4. Aim- Motivation
To develop novel, facile, controlled and reliable routes for different 3D nanostructure arrays for device applications.
How we can realize such 3D nano-structures?
Template Free Method – Chemical Vapor Deposition (CVD)
With Template- Anodic Aluminum Oxide ( AAO template) 4

5. Template Free- CVD Setup
GaN, ZnO, SnSe, SnTe, Te
Precursors Used: Ga2O3 , Ga metal, GaN Powder, NH3 gas and Aqueous NH3, Carbon, graphite powder etc.

6. Template Free- CVD Process

7. Vapor Phase Growth Techniques
1: V-L-S
2: V-S 7

8. Various micro-nano Structures obtained
By CVD Method 8

9. Various micro-nano Structures obtained
By CVD Method 9

10. Various micro-nano Structures obtained
By CVD Method 10

11. Field Emission Smooth Vertical Growth Uniformity Well-patterned arrays
High Density
Sharp tips 11

12. Well aligned / Well patterned Conical shaped
GaN nanorods
1mm2 =1.56×108
GaN nano-rods prepared at 1100 oC (a) top view (b) side view (c) tilted view (d) high magnification tilted view

13. Vapor –Solid (V-S) Growth Mechanism
Growth Mechanism for GaN Nanorods
Vapor –Solid (V-S) Growth Mechanism

14. FE properties of GaN NanoR0d arrays
FE at 1100 oC
Current Stability
Turn-on field = 3.35 Vµm−1 (0.01 mAcm−2) Threshold field= Vµm−1 (1 mAcm−2)
L0w turn on value is due to aligned orientation of GaN rods, aspect ratio, tip radius, density of emitters, density of surface states, morphology, intrinsic properties (such as electronic affinity), dimension of the emitters etc.

15. Comparison of Turn on values of GaN and other different materials
Needle like Nanowires arrays
Conical Shaped nanorods
8.5 V/µm
B. HaJ et al. . Phys. Chem. B 2005, 109,
Well Aligned nano columns
Electric Field (V/µm)
Triangular micro Tubes
Te Petals -Flowers
Thin Nanowires
Tri angular
Cone nanowires
Dandelion Like
Nanowires P
Nanowires
Flower like
Cactus Like
Nanowires
Durian-Like
Grass Like
Nanowires
Needle-like
Nanobelts
Nanowires

16. Photoluminescence GaN
Near-band-edge Emission = 372 nm
***************
Blue Emission= 445 nm (N vacancies)
Blue

17. Photoluminescence GaN
Section No GaN Synthesis and Properties Studies
Near-band-edge Emission = 367 nm
***************
Blue Emission= 553 nm (Ga vacancies)

18. 3D Nano-structure arrays for devices
High Turn-on Field A B
Low Turn-on Field
Same Material
Well patterned nanorods are potential candidate for field emitters /LEDs
Smooth and High density growth is also crucial for device fabrication.
Stable current density also make it important. 18

19. Surface patterning by AAO templates: concept
AAO-Template Method
Surface patterning by AAO templates: concept
1. Y. Lei et al. / Progress in Materials Science 52 (2007) 465– Woo Lee et al. Chem. Rev. 2014, 114, 7487−7556 19

20. Surface patterning by AAO templates: concept
AAO-Template Method
Surface patterning by AAO templates: concept 20

21. Surface patterning by AAO templates: concept
AAO-Template Method
Surface patterning by AAO templates: concept a)
Closed tubes b)
Open tubes c)
Nano-rods d)
Wires with tip
1. Y. Lei, F. Grote et al. / Journal of Power Sources 256 (2014) 37e Y. Lei et al. Nanotechnology 25 (2014) 21

22. Surface patterning by AAO templates: concept
AAO-Template Method
Surface patterning by AAO templates: concept
1. Y. Lei, F. Grote et al. / Journal of Power Sources 256 (2014) 37e Y. Lei et al. Nanotechnology 25 (2014) 22

23. AAO-Template Method Surface patterning by AAO templates: concept
Dimensions controlling of 3D Nano-structure arrays
Anodization
etching
20 min etch
40 min etch
60 min etch
1. Y. Lei, F. Grote et al. / Journal of Power Sources 256 (2014) 37e Woo Lee et al. Chem. Rev. 2014, 114, 7487−7556 23

24. AAO-Template Method Surface patterning by AAO templates: concept
Dimensions controlling of 3D Nano-structure arrays
Nanowire
Nanowire
Nanotube
Nanotube
Nanodot
Liaoyong Wen, Rui Xu, YanMi and Yong Lei, Nature Nanotechnology 12, 244–250 (2017) 24

25. AAO-Template Method Surface patterning by AAO templates: concept
Dimensions controlling of 3D Nano-structure arrays
Liaoyong Wen, Rui Xu, YanMi and Yong Lei, Nature Nanotechnology 12, 244–250 (2017) 25

26. Surface patterning by AAO templates: concept
AAO-Template Method
Surface patterning by AAO templates: concept
Advantage of AAO Template
It offers a convenient and versatile approach
to produce nanostructure arrays of many materials
Controllable morphological features in nanoscale
dimensions, including shape, size, interspace, etc.
Large scale synthesis for practical applications
Applications (Energy Devices)
Super Capacitors
Solar cells
Solar Water Splitting
Batteries 26

27. Department of Physics
University of Gujrat

28. Thanks a lot for your attention
Acknowledgement
Director ORIC/HoD Physics University of Gujrat.
Dr. Waheed S. Khan (Head NanoBio Technology Group) NIBGE .
Prof. Yong Lei Institute of Physics (3D-Nano Group) Technical University
Ilmenau, GERMANY.
Prof. Chuanbao Cao Beijing Institute of Technology, Beijing, P.R.China.
Special thanks to organizers for organizing a nice event, ISS-2017
Thanks a lot for your attention 28

30. Supplementary Material30

31. Supplementary Material31