D. J. O'Connor B.A. Sexton R. St. C. Smart (Eds.)

0-urface Analysis Methods in Materials Science

With 250 Figures

Springer-Verlag Berlin Heidelberg New York London Paris Tokyo Hong Kong Barcelona Budapest

Contents

Part 1 Introduction

1. Solid Surfaces, Their Structure and Composition By C. Klauber and R.St.C. Smart (With 25 Figures) . . . . . . . . . . . . . . . . 3

1.1 Irnportance of the Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 Solid Surfaces of Different Materials . . . . . . . . . . . . . . . . . . . . 7

1.2.1 A Material Under Attack: Aluminium . ......... . .. · 10 1.3 Methods of Surface Analysis ..... ; . .. „ . ... „ . . . . . . . . . 12

1.3.1 Variety of Surface Analytical Techniques . . . . . . . . . . 12 1.4 Structural Irnaging ...... ... . .... .............. : . . . . . . 13

1.4.1 Direct Physical Imaging . . . . . . . . . . . . . . . . . . . . . . . . 13 1.4.2 Indirect Structural Imaging - Relaxation

and Reconstruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 1.5 Composition of the Surface Selvedge . . . . . . . . . . . . . . . . . . . . 21

1.5 .1 Electron Inelastic Mean Free Paths . . . . . . . . . . . . . . . 22 1.5.2 Variation of Elemental Sensitivities . . . . . . . . . . . . . . . 26 1.5.3 Practical Detection Limits . . . . . . . . . . . . . . . . . . . . . . 29 1.5.4 Practical Spatial Limits . . . . . . . . . . . . . . . . . . . . . . . . 30 1.5.5 Chemical State Information . .................. : . 35 1.5.6 Laboratory Standards . . . . . . . . . . . . . . . . . . . . . . . . . . 39 1.5.7 Inter-laboratory Errors . . . . . . . . . . . . . . . . . . . . . . . . . 39

1.6 Defect and Reaction Sites at Surfaces . . . . . . . . . . . . . . . . . . . 40 1.7 Electronic Structure at Surfaces . . . . . . . . . . . . . . . . . . . . . . . . 43 1.8 Structures of Adsorbed Layers . . . . . . . . . . . . . . . . . . . . . . . . . 47 1.9 Structure in Depth Profiles Through Surfaces „ . . . . . . . . . . . . 49 1.10 Specific Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

1.10.1 Grain Structures, Phase Distributions and Inclusions . 52 1.10.2 Fracture Faces and Intergranular Regions ...... :. . . 53 1.10.3 Pore Structures . „ „. „ „ . . „ . „ „ ...... „ „ „ 54 1.10.4 Precipitates, Reaction Products

and Recrystallised Particles on Surfaces . . . . . . . . . . . 55 1.10.5 Magnetic Domains . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

1.11 Technique-Induced Artifacts „ „ „ . „ „ „ : ....... „ „ „ 58 1.11.1 Radiation Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

IX

7.1.1 Theory ........ .. .. ... .. ..... . .... .......... . 7.1.2 Typical Spectrum .. .. ........ .. .............. . 7.1.3 Surface Specificity ........................... .

7 .2 Instrumentation . .. ...................... . ... . ...... ~ . 7.2.1 Essential Components .... . .......... . ........ . 7.2.2 Optional Components .. ............ .. ......... .

7.3 Spectral Information .. .... ... ............ ... .... .... . 7.3.1 Spin-Orbit Splitting .. „ .... „ ... „ ........... .

7.3.2 Chemical Shifts . . ..... . ..... .. .............. . 7.33 Auger Chemical Shifts in XPS ................. . 7.3.4 X-Ray Line Satellites ... .... .. ........... . ... . . 7.3.5 "Shake-up" Lines ............................ . 7.3.6 Ghost Lines ............ .. . ...... . ........... . 7.3.7 Plasmon Loss Lines .......................... .

7.4 Quantitative Analysis .. .............................. . 7 .5 Experimental Techniques ............................. .

7.5.1 Variation of X-Ray Sources .................... . 7.5.2 Depth Profiles ............................... . 7.5.3 Angular Variations ....................... . ... . 7.5.4 Sample Charging . ..... ..... ............. . ... .

7 .6 Comparison with Other Techniques .... .. ... ... . ....... . 7.7 Applications ............. . ..... . ................... . 7 .8 Conclusion ............................... . ........ . References

8. Fourier Transform Infrared Specroscopy of Surfaces By N.K. Roberts (With 12 Figures) ... „ .. „ „. „ .. : ...• ,. „

8.1 Introduction to Fourier Transform Infrared Spectroscopy ... . 8.2 Surface Techniques ............................. . ... .

8.2.1 Diffuse Reflectance Infrared Fourier Transform

8.2.2 8.2.3

References

(DRIFI) ........... ..... . ......... ......... . Attenuated Total Reflectance Spectroscopy (ATR) .. . Photoacoustic Spectroscopy (PAS) .............. .

9. Rutherford Backscattering Spectrometry and Nuclear Reaction Analysis By S.H. Sie (With 8 Figures) ............................. . 9 .1 Principles ......................................... .

9.1.1 Stopping Power ................ . ...... .. .... . 9.1.2 Straggling ......... . ........................ .

9.2 Rutherford Backscattering Spectrometry ................ . 9.2.1 Experimental Considerations ................... .

XII

165 167 168 168 169 172 172 172 173 174 175 175 176 177 178 179 179 180 181 182 183 183 184 184

187 187 189

190 192 198 201

203 204 206 206 207 209

9.2.2 Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209 9.2.3 Special Cases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213

9.3 Nuclear Reaction Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213 9.3.1 Formalism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 9.3.2 Experimental Considerations . . . . . . . . . . . . . . . . . . . . 215 9.3.3 Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216

9.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219

10. Scanning Tunnelling Microscopy By B.A. Sexton (With 15 Figures) . . . . . . . . . . . . . . . . . . . . . . . . . . 221 10.1 History of Development of the STM . . . . . . . . . . . . . . . . . . . . 223 10.2 Theory of Metal-Vacuum-Metal Tunnelling . . . . . . . . . . . . . . . 224 10.3 Experimental Aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226

10.3.1 Piezoelectric Drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . 226 10.3.2 Tue Tunnelling Tip Preparation . . . . . . . . . . . . . . . . . . 227 10.3.3 A Microscope Design . . . . . • . . . . . . . . . . . . . . . . . . . . 227 10.3.4 Electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229

10.4 lmaging Surfaces in Air with the STM . . . . . . . . . . . . . . . . . . 230 10.4.1 Gold Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230 10.4.2 Graphite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232 10.4.3 Lead Dioxide (Pb02) • • • • • • • • • • • • • • • • • • • • • • • • • • 235 10.4.4 Galena (PbS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235

10.5 An Application of Air Microscopy: Compact Disc Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236

10.6 Vacuum Microscopy on Semiconductor Surfaces . . . . . . . . . . 238 10.6.1 Topographie Imaging . . . . . . . . . . . . . . . . . . . . . . . . . . 238 10.6.2 Scanning Tunnelling Spectroscopy (STS) . . . . . . . . . . 239

10.7 Atomic Force Microscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240 10.8 Tue Solid-Liquid Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240 10.9 Adsorbed Molecules and Clusters . . . . . . . . . . . . . . . . . . . . . . . 241 10.10 Surface Modification with the STM . . . . . . . . . . . . . . . . . . . . . 241 10.11 Biological Applications and Langmuir-Blodgett Films . . . . . . 242 10.12 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243

11. Low Energy Ion Scattering By D.J. O'Connor (With 12 Figures) . . . . . . . . . . . . . . . . . . . . . . . . 245 11.1 Qualitative Surface Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 245 11.2 Advantage of Recoil Detection . . . . . . . . . . . . . . . . . . . . . . . . . 247 11.3 Quantitative Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249

11.3.1 Scattered Ion Yield . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249 11.3.2 Differential Scattering Cross Section . . . . . . . . . . . . . . 249

XIII

11.3.3 Charge Exchange ........................ . ... . 11.3.4 Relative Measurements ........................ . 11.3.5 Standards ................................... .

11.4 Surface Structural Analysis ........................... . 11.4.1 Multiple Scattering ........................... . 11.4.2 Impact Collision Ion Surface Scattering (ICISS) .. ~ .

11.5 Experimental Apparatus .............................. . References .......................... · .................. .

12. Reßection High Energy Electron Diffraction By G.L. Price (With 11 Figures) .............. ... .......... . 12.1 Theory . ... .................. . ....... . ... .. ...... . . 12.2 Applications ................................... : ... . References ........ ... ...................... ........... .

13. Low Energy Electron Diffraction By P.J. Jennings (With 11 Figures) ......................... . 13.1 Tue Development of LEED ........ . .................. . 13.2 Tue LEED Experiment ... ..... .... ... . . .... ... ...... .

13.2.1 Sample Preparation ....................... . ... . 13.2.2 Data Collection ............................ . . .

13.3 Diffraction from a Surface ................. . ...... . .. . 13.3.1 Bragg Peaks in LEED Spectra . ................. .

13.4 LEED Intensity Analysis ................. . ... . ....... . 13.5 LEED Fine Structure ........ . ....................... . 13.6 Applications of LEED ............................ . .. .

13.6.1 Determination of the Symmetry and Siz.e of the Unit Mesh ....... . ................. ... .

13.6.2 Unit Meshes for Chemisorbed Systems ........... . 13.6.3 LEED lntensity Analysis ...................... . 13.6.4 Surface Barrier Analysis ...................... .

13.7 Conclusion .......... ..... ......................... . References

14. Ultraviolet Photoelectron Spectroscopy of Solids By R. Leckey (With 8 Figures) ... ......................... . 14.1 Experimental Considerations . ..... .. ........ .. ........ . 14.2 Angle.Resolved UPS ...................... . ......... . References ............................ . ............... .

15. Spin Polarized Electron Techniques By J.L. Robins (With 10 Figures) .................. . ....... . 15.1 Electron Spin .......... .. ............... . .......... .

XIV

250 253 254 257 257 258 260 261

263 265 268 273

275 275 276 279 279 280 281 282 284 285

285 285 286 287 288 289

291 293 295 300

301 302

15.2 Interactions Involving Spin . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303 15.2.1 Spin-Orbit Interactions . . . . . . . . . . . . . . . . . . . . . . . . . 303 15.2.2 Exchange Interactions . . . . . . . . . . . . . . . . . . . . . . . . . . 303 15.2.3 Polarization and Scattering . . . . . . . . . . . . . . . . . . . . . . 304

15.3 Experimental Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305 15.4 Study of Magnetic Properties . . . . . . . . . . . . . . . . . . . . . . . . . . 307 15.5 Sources and Detectors . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . 308 15.6 SEMPA: Scanning Electron Micoscopy

with Polarization Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314

Part m Processes and Applications

16. Materials Technology By R.St.C. Smart (With 9 Figures) ......................... . 16.1 Metals ............................................ . 16.2 Oxides ............................................ . 16.3 Ceramics .......................................... . 16.4 Minerals .................................... . ..... .

16.4.1 Iron Oxides in Mineral Mixtures ................ . 16.4.2 Surface Layers on Minerals .................... . 16.4.3 Mineral Processing of Sulphide Ores ............ . 16.4.4 Adsorption on Soil Minerals ................... .

16.5 Polymers .............................. ............ . 16.5.1 Surface Reactions of Polymers Under UV, Plasma

and Corona Discharges: Chemical Modification and Reaction Layer Thickness Using Angle Resolved XPS .................... .

16.6 Glasses ........................................... . References

17. Characterization of Catalysts by Surface Analysis By B.G. Baker (With 14 Figures) : ......................... . 17.1 Examples of Catalytic Systems ........................ .

17.1.1 Alumina .................................... . 17 .1.2 Tungsten Oxide Catalysts ...................... . 17.1.3 Palladium on Magnesia ....................... . 17.1.4 Cobalt on Kieselguhr Catalysts ................. . 17 .1.5 Iron Catalysts ................. : ............. .

17.2 Conclusion ........................................ . References ............................................ .

319 319 322 323 326 326 327 328 329 330

331 332 335

337 339 339 339 343 344 346 351 351

XV

18. Applications to Devices and Device Materials By J.M. Dell and G.L. Price (With 11 Figures) .. . ............ . 18.1 Device and Circuit Failure Analysis .................... . 18.2 Tue Development of High Quality Ohmic Contacts to GaAs . 18.3 Semiconductor Interfaces: Tue Quantum Well ............ .

18.3.l Double Crystal X-Ray Diffraction ............... . 18.3.2 Reflection High Energy Electron Diffraction ...... . 18.3.3 Photoluminescence ... . ..... ... ............... . 18.3.4 X-Ray Photoelectron Spectroscopy .............. . 18.3.5 Summary ............................ ....... .

References

19. Characterization of Oxidized Surfaces· By J.L. Cocking and G.R. Johnston (With 9 Figures) .......... . 19 .1 Tue Oxidation Problem .............................. . 19.2 Oxidation of Co-22Cr-11Al ........................... .

19.2.1 Chemical Characterization .. . .................. . 19.2.2 Scanning Auger Microscopy . : ............. : ... . 19.2.3 Rutherford Backscattering Analysis ...... . ....... .

19.3 Oxidation of Ni-18Cr-6Al-0.5Y .. .. .. . . ............... . 19.3.1 Extended X-Ray Absorption Fine Structure ....... .

References

20. Coated Steel By R. Payling (With 8 Figures) .. ....... ........... ..... ... . 20. l Applications ............................... ........ .

20.1.1 Grain Boundaries in Steel ..................... . 20.1.2 Steel Surface ... ..... ........................ . 20.1.3 Alloy Region . ....... .. . . .. .. . .............. . 20.1.4 Metallic Coatings ............................ . 20.1.5 Treated Metallic Coating Surface .. .. . .......... . 20.1.6 Metal-Polymer Interface ............... . ....... . 20.1.7 Polymer Surface ...... . ..... .. ............... .

20.2 Conclusion ....... .... .. .... .. .... .. ............... . References

21. Thin Film Analysis By G.C. Morris (With 9 Figures) .. ............. ..... ...... . 21.1 Thin Film Photovoltaics .. . ........ ... ............... .

21.1.1 Use for Solar Electricity ....................... . 21.1.2 Tue Thin Film Solar Cell:

Glass/ITO/nCdS/pCdTe/Au .................... . 21.2 Film Purity ................................. ....... .

XVI

353 354 356 361 362 363 364 367 369 370

371 372 373 373 374 375 381 381 386

387 388 388 389 392 392 396 397 398 400 401

403 404 404

405 406

21.2.1 Low Level lmpurities - Qualitative .............. . 21.2.2 Low Level lmpurities - Quantitative ... .......... . 21.2.3 Doping Profiles in Thin Films .................. .

21.3 Composition and Thickness of Layered Films ............ . 21.3.1 Composition Gradation in Films,

e.g. Cd„Hg1-:1: Te Films on Platinum ............. . 21.3.2 Thin Overlayers on Films ..................... .

21.4 Beam Effects in Thin Film Analysis ..... .............. . 21.5 Conclusion ............................. ........... . References

22. ldentification of Adsorbed Species By B.G. Baker (With 10 Figures) .............. ............ . 22.1 Examples of Adsorption Studies ......... .............. .

22.1.1 Nitric Oxide Adsorption on Metals .............. . 22.1.2 Aurocyanide Adsorption on Carbon ............. . 22.1.3 Adsorbed Methoxy on Copper and Platinum ...... .

22.2 Conclusion ........................................ . References

Part IV Appendix

Acronyrm Used in Surface and Thin Film Analysis

406 408 409 410

410 410 414 415 415

417 417 417 422 425 429 429

By C. Klauber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433

Surface Science Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 439

Subject Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 447

XVII