School of Materials Engineering Thin Films and Interfaces Atomic Force Microscopy Studies of Gold...
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![Page 1: School of Materials Engineering Thin Films and Interfaces Atomic Force Microscopy Studies of Gold Thin Films Dara Gough Advisor: Prof. King.](https://reader035.fdocuments.in/reader035/viewer/2022062300/56649d555503460f94a33011/html5/thumbnails/1.jpg)
School of Materials EngineeringThin Films and Interfaces
Atomic Force Microscopy Studies of Gold Thin Films
Dara Gough
Advisor: Prof. King
![Page 2: School of Materials Engineering Thin Films and Interfaces Atomic Force Microscopy Studies of Gold Thin Films Dara Gough Advisor: Prof. King.](https://reader035.fdocuments.in/reader035/viewer/2022062300/56649d555503460f94a33011/html5/thumbnails/2.jpg)
School of Materials EngineeringThin Films and Interfaces
Overview
• Brief Background• Purpose of the project• Project objectives• Why use gold films?• Experimental approach• Setbacks• Results
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School of Materials EngineeringThin Films and Interfaces
Background
• The angle formed by the grain surfaces at the grain boundary is constant
• The triple junction was ignored in previous research– It is now believed to
have a line tension associated with it that affects the grains
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School of Materials EngineeringThin Films and Interfaces
Background
• Theory: Groove (grain boundary and triple junction) depths increase with decreasing grain size
– The effects may be significant in Nano-scale
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School of Materials EngineeringThin Films and Interfaces
PurposeEventual Goal:• Triple junctions may be “doped” to high levels (Via
Diffusion Along the Triple Junction) to make them conductive in an insulating material, or magnetic, or otherwise active regions of near-atomic dimension.
Courtesy of Prof. King
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School of Materials EngineeringThin Films and Interfaces
Purpose• To study the
development of grooves as a function of the film thickness – The relative height (Hr)
is approximately equivalent to 4/3 and is derived by the expression:
zg
zgb
ztj
gbg
tjgr zz
zzH
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School of Materials EngineeringThin Films and Interfaces
Objectives• To create gold thin films of varying
thicknesses• To anneal the film samples• To obtain surface profiles of the
samples
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School of Materials EngineeringThin Films and Interfaces
Objectives
• To analyze the surface profiles and obtain data points– The data points are the height
differences between:• The center of the grain and the middle of
the grain boundary• The center of the grain and the triple
junction
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School of Materials EngineeringThin Films and Interfaces
Why Gold?
• Gold is the ideal metal for this experiment because:– It is polycrystalline – It does not oxidize in atmospheric
conditions– It evaporates easily in high temperature-
low pressure environment
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School of Materials EngineeringThin Films and Interfaces
Experimental Approach
• Evaporation coat glass substrates with a gold thin film– Thicknesses ranging
from (150-450nm)
• Anneal the samples at 350°C for 72 hours– To create dome-shaped
grains that are approximately equal in size to the film thicknessImage courtesy of Prof. King
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School of Materials EngineeringThin Films and Interfaces
Experimental Approach
• Obtain profiles of the gold film using the Atomic Force Microscope (AFM)
– Multiple images must be taken of each film in order to obtain hundreds of data points
12 x 12 microns
Image courtesy of Raghavan Narayanan
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School of Materials EngineeringThin Films and Interfaces
Experimental Approach
• The next step in the project is to analyze the images– This is done using Scanning Probe
Microscopy Software – The software analyzes changes in height
along the surface and provides relative height differences
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School of Materials EngineeringThin Films and Interfaces
Setbacks
• Problems:– Multiple scan errors
with the AFM– Vibration lines in
images– Improper
engagement of the tip
1.0 x 1.0 micron
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School of Materials EngineeringThin Films and Interfaces
SetbacksThis is an ideal image obtained using the AFM
1.0 x 1.0 micron
This is the type of image obtained from the AFM recently6 x 6 microns
Image courtesy of Raghavan Narayanan
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School of Materials EngineeringThin Films and Interfaces
Setbacks
• My initial set of gold films was over-annealed– This resulted in the gold receding from
the substrate
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School of Materials EngineeringThin Films and Interfaces
SetbacksThis optical microscopy image was taken using reflected light
This is the same image taken using transmitted light
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School of Materials EngineeringThin Films and Interfaces
Results
• I was able to begin analyzing an image provided by Raghavan Narayanan
• Average grain size is 1270 nm2 (counted 252 grains)
1.0 x 1.0 micron
Image courtesy of Raghavan Narayanan
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School of Materials EngineeringThin Films and Interfaces
ResultsHr Distribution
0
5
10
15
20
25
30
35
Data Range
Fre
qu
en
cy
170 Data Points
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School of Materials EngineeringThin Films and Interfaces
Future Work
• Take more surface profiles using the AFM– Over a wider variety of film thicknesses
(grain sizes)
• Analyze the surface profiles using the Scanning Probe Microscopy Software
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School of Materials EngineeringThin Films and Interfaces
Acknowledgements
• I would like to thank the National Science Foundation (REU Grant DMR-0243830) for financing my research alongside the Department of Energy
• I would like to thank Prof. Alex King for his support and guidance
• I would also like to thank Raghavan Narayanan for his assistance throughout the course of the project
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School of Materials EngineeringThin Films and Interfaces
(Questions)