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E-raamat: Physics of Schottky Electron Sources: Theory and Optimum Operation [Taylor & Francis e-raamat]

  • Formaat: 266 pages, 7 Illustrations, color; 168 Illustrations, black and white
  • Ilmumisaeg: 25-Jul-2014
  • Kirjastus: Pan Stanford Publishing Pte Ltd
  • ISBN-13: 9780429074226
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  • Taylor & Francis e-raamat
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Physics of Schottky Electron Sources: Theory and Optimum OperationSuurem pilt
  • Formaat: 266 pages, 7 Illustrations, color; 168 Illustrations, black and white
  • Ilmumisaeg: 25-Jul-2014
  • Kirjastus: Pan Stanford Publishing Pte Ltd
  • ISBN-13: 9780429074226
Teised raamatud teemal:
Taylor & Francis e-raamatudRohkem infot Taylor & Francis e-raamatute kohta
Raamatu kodulehekülg: https://www.taylorfrancis.com/books/9780429074226
Drawing from her work as a PhD candidate in charged particle optics at Delft University of Technology, Bronsgeest examines the Schottky electron source, the predominant type used in electron beam equipment. Increasingly more stringent performance requirements mean its properties must be understood more thoroughly to determine the best possible performance for a given application, which operating parameters are associated with that performance, and how stable the "best" performance is. She covers electron emission from a surface, emission from a Schottkey emitters, emission from the end facet, the final beam for applications, geometrical stability, and optimum operations. Distributed in the US by CRC Press. Annotation ©2014 Ringgold, Inc., Portland, OR (protoview.com)

The Schottky electron emitter is a predominant electron-emitting source in today’s electron beam equipment. This book comprehensively covers the Schottky emitter, dealing with its theoretical as well as practical aspects. The main questions that are addressed in this book are: what is the Schottky electron emitter? How does it work? And how do its properties affect the performance of electron beam equipment?

The focus is on the direct link between the operating conditions of the source and the properties of the beam at the target level. This coupling is made clear by discussing the effect of the operating conditions and the geometry of the source and gun on the emission properties of the emitting surface, the effect of Coulomb interactions on the brightness and energy spread in the first few millimeters of the beam path, and the effect of the operating conditions and the shape of the emitter on the consequences of the beam at the target. The final chapter combines all these effects to demonstrate that there is a trade-off to be made between brightness, energy spread, and shape stability.

Preface ix
Introduction 1(6)
1 Electron Emission from a Surface
7(22)
1.1 The Potential Energy Barrier at a Surface
7(2)
1.2 Emission by Heating
9(3)
1.3 The Effect of an Electric Field on the Potential Energy Barrier at a Surface
12(4)
1.4 Emission by Heating and Applying an Electric Field
16(13)
1.4.1 Escape Probability
16(6)
1.4.2 Current Density
22(3)
1.4.3 Energy Distributions
25(4)
2 Emission from a Schottky Emitter
29(20)
2.1 Work Function Variations across the Emitter Surface
30(2)
2.2 Applying a Bias
32(6)
2.3 Applying a Heating Current
38(7)
2.3.1 Temperature
38(4)
2.3.2 Tip Protrusion [ Field Strength)
42(2)
2.3.3 Surface Properties (Work Function)
44(1)
2.4 Total Emission Current
45(4)
3 Emission from the End Facet
49(46)
3.1 The Facet Extractor Lens
50(9)
3.1.1 At the Facet
50(2)
3.1.2 Lens Properties
52(3)
3.1.3 Behind the Extractor
55(1)
3.1.3.1 The angular intensity of the source
55(2)
3.1.3.2 The full facet emission pattern
57(2)
3.2 The Effect of the Voltage Settings
59(10)
3.2.1 Different Options
59(1)
3.2.2 The Effect of Changing the Extraction Voltage
60(2)
3.2.2.1 From the facet toward the extractor
62(7)
3.3 The Effect of Emitter Geometry
69(6)
3.3.1 Tip End
69(2)
3.3.2 Tip Size
71(2)
3.3.3 Cone Shape
73(2)
3.4 Schottky Plots
75(6)
3.5 The Effect of the Heating Current
81(14)
3.5.1 A Temperature-Dependent Work Function
84(5)
3.5.2 The Predicted Effect on the Emission Pattern
89(6)
4 The Final Beam for Applications
95(52)
4.1 Imaged by the Electron-Optical System: The Virtual Source
96(12)
4.1.1 Imaginary Cold Schottky Source
97(3)
4.1.2 Heated Schottky Source
100(8)
4.2 Current in the Source Image: Practical Brightness
108(8)
4.2.1 The Definition of Practical Brightness
109(4)
4.2.2 How to Get the Practical Brightness of a Source?
113(1)
4.2.3 The Intrinsic Practical Brightness for Thermionic, Schottky, and Cold Field Emission Electron Sources
114(2)
4.3 Total Probe Size: Source Image Plus Diffraction Plus Aberration Contributions
116(3)
4.4 The Effect of Electron-Electron Interactions in the Beam
119(23)
4.4.1 Simulations
121(1)
4.4.1.1 General equations
122(3)
4.4.1.2 Application to Schottky emitters
125(5)
4.4.1.3 Adding contributions together
130(4)
4.4.2 The Boersch Effect Extracted from Energy Spread Data
134(1)
4.4.2.1 Function to represent the Boersch effect
134(1)
4.4.2.2 Total energy distribution measurement
135(1)
4.4.2.3 Intrinsic contribution
136(1)
4.4.2.4 Fit results
137(3)
4.4.2.5 Comparison with theory
140(1)
4.4.2.6 Discussion
141(1)
4.5 Summarizing: The Beam Properties Relevant to Electron Optical Systems
142(5)
5 Geometrical Stability
147(68)
5.1 Observed Geometrical Changes
147(4)
5.2 Equilibrium Crystal Shapes
151(5)
5.3 Tip Size Growth
156(8)
5.3.1 The Continuum Model: Tip Size Growth at Low Fields
156(6)
5.3.2 Tip Size Growth at High Fields
162(2)
5.4 Changes of the End Facet Geometry
164(13)
5.4.1 Evidence of the Tip-Emitter Interplay
165(3)
5.4.2 Reversible Changes of the End Facet
168(1)
5.4.2.1 Monitoring with the emission pattern
168(8)
5.4.2.2 Monitoring with the Schottky plot slope
176(1)
5.5 Collapsing of the End Facet
177(31)
5.5.1 The Step-Flow Model
178(4)
5.5.1.1 Application to Schottky emitters
182(5)
5.5.1.2 Discussion
187(2)
5.5.2 Tip-Emitter Interplay
189(1)
5.5.2.1 Experiments
190(2)
5.5.2.2 General system check: no-collapse operation
192(1)
5.5.2.3 Collapsing analysis
193(3)
5.5.3 (A)symmetry
196(5)
5.5.4 Detailed Geometrical Description
201(7)
5.6 The Effect on Beam Properties
208(3)
5.6.1 Facet Size Changes
208(2)
5.6.2 Facet Collapse
210(1)
5.7 Concluding Remarks
211(4)
6 Optimum Operation
215(16)
6.1 Maximum Performance for Different Applications
216(8)
6.1.1 Maximum Performance from a Static Emitter Shape
216(4)
6.1.2 Geometrical Limitations
220(4)
6.2 Source-Monitoring Tools
224(3)
6.2.1 Schottky Plot Slope
225(1)
6.2.2 Total Emission Current
226(1)
6.2.3 Facet Emission Pattern
226(1)
6.3 Practical Considerations
227(4)
6.3.1 For Users
227(1)
6.3.2 For System Manufacturers and Experimental Setups
228(3)
Appendix A Procedures for Monitoring in a Few Commercial Systems 231(8)
Appendix B Procedure to Characterize System Performance 239(4)
Bibliography 243(8)
Index 251
Merijn Bronsgeest obtained her M.Sc. cum laude in 2004 at the Materials Science & Engineering department at Delft University of Technology, the Netherlands, being honored with the award for Best MS&E Graduate of the Year. She earned her Ph.D. in applied physics cum laude from the same university in 2009 for her work on Schottky electron sources, which was a project in collaboration with FEI Company. In 2009 Merijn went to the University of Maryland to work on carbon nanotubes. In a first project, she designed and fabricated a write-one-read-many memory based on carbon nanotube transistors. After that, she focused on the characterization of thermal transport properties of carbon nanotubes with an in situ TEM technique. In 2011 she participated in a session of the Global School of Advanced Studies on graphene in Grenoble, France. This led to her moving to Grenoble in 2012 to work at CEA as a Eurotalents fellow on new two-dimensional materials.
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