Thermal stability, atomic vibrational dynamics, and superheating of confined interfacial Sn layers in Sn/Si multilayers
Abbreviated Journal Title
Phys. Rev. B
ALPHA-SN; TIN NANOPARTICLES; LATTICE-DYNAMICS; PHASE-TRANSITION; THIN-FILMS; MOSSBAUER; SILICON; ALLOYS; GROWTH; SPECTROSCOPY; Physics, Condensed Matter
Multilayers composed of materials with low (Sn) and high (Si) bulk melting points were grown at room temperature by ultrahigh vacuum deposition. Sn-119 Mossbauer spectroscopy has been used to investigate the temperature dependence of the Debye-Waller factor f, the mean-square displacement, and the mean-square velocity of Sn-119 nuclei in ultrathin (10 angstrom thick) alpha-like Sn layers embedded between 50 angstrom thick Si layers. The f factor was found to be nonzero with a value of 0.036 +/- 0.009 even at 450 degrees C. This provides unequivocal proof of the solid state of the confined alpha-like Sn layers at least up to 450 degrees C. Melting can only be achieved by superheating to T > 450 degrees C. This temperature is significantly higher than the melting temperature of bulk beta-Sn (231.9 degrees C) and of a nonconfined epitaxial alpha-Sn single layer grown on InSb(111) (170 degrees C) previously reported in the literature [T. Osaka , Phys. Rev. B 50, 7567 (1994)]. Our molecular dynamics calculations show that melting of bulk-like alpha-Sn starts at similar to 380 degrees C and is complete at similar to 530 degrees C according to the Lindemann criterion. Since we still observe the solid state at 450 degrees C for the confined alpha-like Sn films, considerable superheating is observed for this system. The stability of the ultrathin confined alpha-like Sn layers arises from electronic interactions with the surrounding Si layers, as evidenced by the Mossbauer chemical shift.
Physical Review B
"Thermal stability, atomic vibrational dynamics, and superheating of confined interfacial Sn layers in Sn/Si multilayers" (2006). Faculty Bibliography 2000s. 4680.