Advanced design of periodical structures by laser interference metallurgy in the micro, nano scale on macroscopic areas [Elektronische Ressource] / von Andrés Fabián Lasagni

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Informations

• Publié par: universitat_des_saarlandes
• Publié le: 01 janvier 2007
• Nombre de lectures: 6
• Langue: English
• Poids de l'ouvrage: 30 Mo

Extrait

Advanced design of periodical structures by laser interference
metallurgy in the micro/nano scale on macroscopic areas








Dissertation

zur Erlangung des Grades des
Doktors der Ingenieurwissenschaften
der Naturwissenschaftlich-Technischen Fakultät III
Chemie, Pharmazie, Bio- und Werkstoffwissenschaften
der Universität des Saarlandes









von

Andrés Fabián Lasagni







Saarbrücken, Germany
2006

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Tag der Einreichung: 13. Juni 2006
Tag des Kolloquiums: 8. Dezember 2006

Dekan: Prof. Dr. Kaspar Hegetschweiler

Berichterstatter: Prof. Dr. F. Mücklich, Universität des Saarlandes
Prof. Dr. W. Arnold, Universität des Saarlandes
Prof. Dr. H.P. Degischer, TU - Wien
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Dedicado a mis padres Renata y Norberto,
a la “nonna” Emma, a mis hermanos Fernando,
Reny y Viviana, y a mi amor Barbara


































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vi Contents

Contents

Symbols and abbreviations xii
Abstract xvii
Summary/Zusammenfassung xix
1- Introduction 1
2- Patterning techniques 5
2.1- Optical lithography 7
2.2- E-Beam 9
2.3- Imprint lithography 10
2.4- Replica moulding 12
2.5- Microcontact printing 13
2.6- Laser writing 15
2.7- Holographic patterning 16
2.8- Direct laser interference patterning 19
2.8.1- Semiconductors 20
2.8.2- Polymers 21
2.8.3- Metals 22
3- Review of laser-matter interaction 25
3.1- Fundamental optics properties 25
3.2- Optical response in metals 27
3.2.1- Drude theory 27
3.2.2- Hagen-Rubens relation 30
3.3- Factors which affect the reflectance in metals 30
3.3.1- Effect of temperature 31
3.3.2- Effect of angle of incidence 32
3.3.3- Effect of surface roughness 33
3.4- Mechanisms of structuring by laser light 34
viiContents

3.4.1- Photo-thermal and photo-chemical processes 34
3.4.2- Effect of laser-pulse duration 35
3.4.2.1- Femtosecond’s laser pulses 36
3.4.2.2- Nano- and picosecond’s laser pulses 38
4- Interference Theory, Inverse Problem and Thermal Simulation 39
4.1- Interference theory 39
4.2- Inverse problem 42
4.3- Thermal simulation 48
5- Experimental procedure 53
5.1- Samples preparation 53
5.1.1- Thin films 53
5.1.2- Bulk metals 54
5.2- Laser interference structuring system 54
5.3- In-situ time-resolved electrical resistance measurements 56
5.4- Sample characterisation 56
5.4.1- Topographic characterisation 56
5.4.2- SEM and EDS characterisation 57
5.4.3- Cross sectional analysis and TEM foil preparation 57
5.4.4- High-angle annular dark-field microscopy investigations 59
5.5- Characterisation of optical properties 59
5.6- Characterisation of tribological 60
6- Micro/nano structuring of metallic systems 63
6.1- Single-layer systems 63
6.1.1- Structuring regimes 63
6.1.2- Thermal simulation 66
6.1.3- Discussion 67
6.2- Two layer systems - Case A: metal with the higher melting point on top 69
6.2.1- Structuring regimes 69
viii Contents

6.2.2- Thermal simulation 71
6.2.3- Multi-beam experiments 76
6.2.4- Aspect ratio of line- and dot-type structures 81
6.2.5- EDS Analysis 81
6.2.6- Cross sectional analysis 84
6.2.7- Effect of the layer thickness on the structure depth 85
6.2.8- Nanohardness investigations 87
6.2.9- Discussion 88
6.2.9.1- Line-type structures 88
6.2.9.2- Dot-type 93
6.2.9.3- General structuring mechanism 95
6.3- Two layer systems - Case B: metal with the lower melting point at the bottom 96
6.3.1- Structuring regimes 96
6.3.2- Thermal simulation 97
6.3.3- EDS and cross-sectional analyses 100
6.3.4- Discussion 102
6.4- Structuring of bulk materials 103
6.4.1- Effect of period
6.4.2- of laser fluence 106
6.4.3- Effect of number of pulses 106
6.4.4- Discussion 107
6.5- Long-range formation of intermetallic pattern 108
6.5.1- Sample Fe(30nm)/Al(120nm) 108
6.5.2- Al(30nm)/Fe(120nm) 111
6.5.3- Sample Fe(75nm)/Cu(30nm)/Fe(55nm) 112
6.6- Time - resolved electrical resistance measurements 116
7- Modulation of optical and tribological properties 119
7.1- Optical properties
7.1.1- Optical properties of structured bulk materials 120
ixContents

7.1.1.1- Experimental results 120
7.1.1.2- Numerical calculations 123
7.1.1.3- Discussion 124
7.1.2- Optical reflectance of structured bi-metallic thin films 126
7.2- Tribological performance of structured bulk materials 127
7.2.1- Results and discussion 128
8- Conclusions and outlook 131
List of publications 135
References 137
Appendixes
Appendix 1- Examples of possible interference patterns 147
Appendix 2-The inverse problem 151 3- Properties of metals 157
Appendix 4- Production of periodical gratings in mixed oxide films 161






















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