Effects of rapid thermal annealing on crystallinity and Sn surface segregation of ${\mathrm{Ge}}_{1-{\boldsymbol{x}}}{\mathrm{Sn}}_{{\boldsymbol{x}}}$ films on Si (100) and Si (111)

Abstract

Germanium-tin films with rather high Sn content (28.04% and 29.61%) are deposited directly on Si (100) and Si (111) substrates by magnetron sputtering. The mechanism of the effect of rapid thermal annealing on the Sn surface segregation of Ge 1−x Sn x films is investigated by x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The x-ray diffraction (XRD) is also performed to determine the crystallinities of the Ge 1−x Sn x films. The experimental results indicate that root mean square (RMS) values of the annealed samples are comparatively small and have no noticeable changes for the as-grown sample when annealing temperature is below 400 • C. The diameter of the Sn three-dimensional (3D) island becomes larger than that of an as-grown sample when the annealing temperature is 700 • C. In addition, the Sn surface composition decreases when annealing temperature ranges from 400 • C to 700 • C. However, Sn bulk compositions in samples A and B are kept almost unchanged when the annealing temperature is below 600 • C. The present investigation demonstrates that the crystallinity of Ge 1−x Sn x /Si (111) has no obvious advantage over that of Ge 1−x Sn x /Si (100) and the selection of Si (111) substrate is an effective method to improve the surface morphologies of Ge 1−x Sn x films. We also find that more severe Sn surface segregation occurs in the Ge 1−x Sn x /Si (111) sample during annealing than in the Ge 1−x Sn x /Si (100) sample.

Review of Si-Based GeSn CVD Growth and Optoelectronic Applications

“…[ 33 , 34 , 35 , 36 , 37 ]. Growing high-quality GeSn layers with relatively high Sn contents has different challenges, e.g., Sn segregation during growth and the poor thermal stability of SnGe layers [ 38 , 39 , 40 , 41 ]. These issues root from the low solid solubility of Sn in Ge (<1%) and the large lattice mismatch between Si or Ge and GeSn.…”

Single-crystalline GePb alloys formed by rapid thermal annealing-induced epitaxy

“…This suggests that the crystalline GePb formed after annealing at the temperature of 400 • C. It can be observed that when the annealing temperature increased to 700 • C, the diffraction peak shoulder at around 65.95 • disappeared. Hence, we suggest that the incorporation of Pb in Ge was varied during the crystallization of GePb when the annealing temperature was higher than 550 • C, which is the same phenomenon that occurs in the GeSn layers [51]. From Bragg's law,…”

Structural, optical, and magnetic properties of Ag+, Mn+ and Ar+ ions implanted ZnO thin films: effect of implantation dose and stopping energy

“…It is evident that the peak intensity reduces significantly for high dose of implantation. A reduction in XRD peak intensity is related to a decrease in the degree of crystallinity, 43 which is commonly observed in implanted oxide materials as a result of damage induced by implanted ions. 44 Apart from the change in intensity, a visual inspection shows a shift in peak position.…”