• Technological importance. These alloys are perfect solders for semiconductor industry.
• Fundamental interest. The surface structure study of liquid binary alloys can be a test for theoretical models.
• In addition, liquid surfaces of pure Au, Si and Ge are hardly accessible for studying due to high melting temperature, but the eutecic melting temperature is below 400 C far below melting points of pure elements.
• Chemical reactions of liquid surfaces of these systems like oxidation are very interesting to study.

Achievements

AuSi and AuGe eutectic alloys have been studied at ChemMat-CARS, APS, Argonne, IL. The results were reported at APS User's Meeting 2004, NSLS User's Meeting 2004 and a paper on the Au82Si18 eutectic was published Science in 2006

• O. G. Shpyrko, R. Streitel, V. S. K. Balagurusamy, A. Y. Grigoriev, M. Deutsch, B. M. Ocko, M. Meron, B. H. Lin, and P. S. Pershan, "Surface crystallization in a liquid AuSi alloy",Science 313, 77 (2006).

• AuSi and AuGe are unique low melting temperature eutectic alloys (compare to melting points of components)
• Low vapor pressure allows UHV studies
• In spite of similarity between two alloys their surfaces have significantly different structure
• Surface form factor of the AuSi eutectic alloy is 20 times higher than for any other studied metallic systems including the AuGe eutectic
• The surface of the Au82Si18 alloy has 2D in-plane order corresponding to AuSi2. There is no known stable bulk phase with this composition.
• Studies along the eutetic line of ternary Au-Si-Ge indicate that the ordered AuSi2 phase vanishes somewhere between 2.5 atm% Ge and 6.5atm%.
• Surface structure of the Au-Si-Ge system can not be explained with models previously developed for pure metals and alloys

1. In situ investigation of stage of the formation of eutectic alloys in Si-Au and Si-Al systems
   Bokhonov, B.; Korchagin, M.,
   Journal of Alloys and Compounds 312, 238 (2000)
2. Assembling three-dimensional microstructures using gold-silicon eutectic bonding
   Tiensuu, A.-L.; Bexell, M.; Schweitz, J.-A.; Smith, L.; Johansson, S.
   ensors and Actuators A (Physical) A45, 227 (1994)
3. Ellipsometrical studies on the Au/Si(111) system
   Muemmler, K.; Wissmann, P.
   Thin Solid Films 317, 193 (1998)
4. Field emission properties of Au-Si eutectic
   Zhimov, V.V.; Bormatova, L.; Givargizov, E.I.; Plekhanov, P.S.; Son, U.T.; Galdetsky, A.V.; Belyavsky, B.A.
   Applied Surface Science 94-95, 144 (1996)
5. Low-temperature silicon wafer-to-wafer bonding using gold at eutectic temperature
   Wolffenbuttel, R.F.; Wise, K.D.
   Sensors and Actuators A (Physical) A43, 223 (1994)
6. Structure of liquid alloys of the Au-Si and Au-Ge systems
   Waghorne, R.M.; Rivlin, V.G.; Williams, G.I.
   Journal of Physics F (Metal Physics) 6, 147 (1976)
7. Au-Si eutectic alloy formation by Si implantation in polycrystalline
   Kennedy, V.J.; Demortier, G.
   Nuclear Instruments & Methods in Physics Research, Section B (Beam Interactions with Materials and Atoms) 171, 325 (2000)
8. The wettability of silicon carbide by Au-Si alloys
   Y.V. Naidich, V. Zhuravlev, N. Krasovskaya
   Materials Science and Engineering A245, 293 (1998)
9. Electrical and optical properties of melting Au/Si eutectics on Si(111)
   Brueggemann, M.; Muemmler, K.; Wissmann, P.
   Fresenius' Journal of Analytical Chemistry, 358, 179 (1997)
10. Localized silicon fusion and eutectic bonding for MEMS fabrication and packaging
    Cheng, Y.T.; Lin, L.; Najafi, K.
    Journal of Microelectromechanical Systems 9, 3 (2000)
11. 3D characterization of the eutectic Au-Si alloy by using a nuclear microprobe
    Demortier, G.; Mathot, S.
    Scanning 13, 350 (1991)
12. The gold-silicon phase diagram
    Anantatmula, R.P.; Johnson, A.A.; Gupta, S.P.; Horylev, R.J.
    Journal of Electronic Materials 4, 445 (1975)
13. Eutectic reactions and textures of Au-Si alloy films on single-crystal silicon
    Kato, H.
    Japanese Journal of Applied Physics, Part 1 (Regular Papers & Short Notes) 28, 953 (1989)
14. Use of wetting angle measurements in reliability evaluations of Au-Si eutectic die attach
    Mencinger, N.P.; Carthy, M.P.; McDonald, R.C.
    23rd Annual Proceedings Reliability Physics 1985 (Cat. No. 85CH2113-9), 173 (1985)
15. Wetting of quartz surfaces by Au-Si eutectic melt (MOS structures)
    Tu, K.N.; Libertini, S.H.
    Journal of Applied Physics 48, 420 (1977)
16. Determination of the solubility of silicon in gold and the gold-silicon eutectic composition using a new quantitative metallographic technique
    Johnson, D.N.; Biagtan, E.C.; Johnson, A.A.
    Scripta Metallurgica 21, 1689 (1987)
17. The nature of atomic ordering in eutectic Au-Si and Al-Si alloys
    Dutchak, Ya.I.; Frenchko, V.S.
    Soviet Physics Journal, 122 (1975)
18. Surface cracking in gold-silicon alloys
    Johnson, D.N.; Johnson, A.A.
    Solid-State Electronics 27, 1107 (1984)
19. X-ray investigation of some eutectic alloys in the liquid state
    Dutchak, J.I.; Frenchko, V.S.; Klanichka, V.M.; Kuznetsova, L.S.
    Acta Crystallographica, Section A (Crystal Physics, Diffraction, Theoretical and General Crystallography) A28, S127 (1972)