The structures of normal and supercooled liquid silicon metal and SiGe alloy

The atomic structures of liquid Si metal and SiGe alloy in the normal and supercooled liquid states have been measured by X-ray diffraction from aerodynamically levitated and laser heated liquid droplets. The measurements covered a wide range of scattering vector Q (0.8-20 A(-1)) and a wide temperature range that extended into the supercooled region. The present results on liquid Si confirm earlier measurements that showed a decrease in first-shell coordination with increased supercooling. For liquid SiGe, the shoulder on the high-Q side of the first peak in the structure factor S(Q) sharpens with increased supercooling, suggesting an increase in covalent bonding and development of chemical short-range order. (c) 2007 Elsevier B.V. All rights reserved.