TY - GEN
T1 - Crystal growth of SixGe1-x using the vertical Bridgman technique
T2 - 61st International Astronautical Congress 2010, IAC 2010
AU - Woodacre, Jeffrey K.
AU - Labrie, D.
AU - Shemirani, M. M.
AU - Saghir, M. Z.
PY - 2010
Y1 - 2010
N2 - Silicon-Germanium single crystals play an important role in the electronic and optoelectronic industries. The SiGe phase diagram suggests that it suffers from strong segregation during the growth. Fluctuations in growth parameters are attributed to convection current occurring in the molten Si 1-xGex. In light of the large density difference between molten Si and Ge, gravity plays a central role in the inducement of convection flows in the molten alloy. This points out to the importance of performing SiGe crystal growth on a long duration microgravity platform to extract its fundamental properties. Toward the preparation of such experiments, crystal growth of SixGe1-x. with x = 0.25, and 0.15 was carried out using the vertical Bridgman technique in the laboratory. The growth was performed in a three zone resistive furnace consisting of PtRh heating wire. The growth ampoules were translated at a speed of 0.3 mm/hr and 0.4 mm/hr where the temperature gradient was along the g vector. The grown SiGe samples were 2.5 cm diameter by 9 cm long. The samples were sliced axially, polished, and etched to study the evolution of the growth striations along the growth axis. The interface shape changed from concave to planar or convex as the growth proceeded. Electron Microprobe Analysis was carried out to measure the Silicon composition along and transverse to the growth axis. The axial Si composition was analyzed using a simple one dimensional model assuming full mixing of the melt during growth and a segregation coefficient which varies with Silicon content in the melt given by the phase diagram of SiGe alloy.
AB - Silicon-Germanium single crystals play an important role in the electronic and optoelectronic industries. The SiGe phase diagram suggests that it suffers from strong segregation during the growth. Fluctuations in growth parameters are attributed to convection current occurring in the molten Si 1-xGex. In light of the large density difference between molten Si and Ge, gravity plays a central role in the inducement of convection flows in the molten alloy. This points out to the importance of performing SiGe crystal growth on a long duration microgravity platform to extract its fundamental properties. Toward the preparation of such experiments, crystal growth of SixGe1-x. with x = 0.25, and 0.15 was carried out using the vertical Bridgman technique in the laboratory. The growth was performed in a three zone resistive furnace consisting of PtRh heating wire. The growth ampoules were translated at a speed of 0.3 mm/hr and 0.4 mm/hr where the temperature gradient was along the g vector. The grown SiGe samples were 2.5 cm diameter by 9 cm long. The samples were sliced axially, polished, and etched to study the evolution of the growth striations along the growth axis. The interface shape changed from concave to planar or convex as the growth proceeded. Electron Microprobe Analysis was carried out to measure the Silicon composition along and transverse to the growth axis. The axial Si composition was analyzed using a simple one dimensional model assuming full mixing of the melt during growth and a segregation coefficient which varies with Silicon content in the melt given by the phase diagram of SiGe alloy.
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M3 - Conference contribution
AN - SCOPUS:79959438186
SN - 9781617823688
T3 - 61st International Astronautical Congress 2010, IAC 2010
SP - 2908
EP - 2913
BT - 61st International Astronautical Congress 2010, IAC 2010
Y2 - 27 September 2010 through 1 October 2010
ER -