Preparation of Ge_1-yC_y Alloys by C Implantation into Ge Crystal and Their Raman Spectra

Abstract

We attempted to prepare Ge1-y C y alloys by implantation of C atoms into Ge crystals and post-annealing. For samples annealed at temperatures higher than 450°C, X-ray diffraction (XRD) spectra indicated that the Ge1-y C y alloys were successfully prepared. The highest substitutional C content was about 1 at.%. The optimum annealing temperature to incorporate C atoms into the substitutional sites was 450–500°C. We also investigated the dependence of the Raman intensity of the Ge–C local mode on the substitutional C content. The intensity of the Ge–C local mode was found to increase in proportion to the substitutional C content. Furthermore, the relationship between Ge–C peak intensity and substitutional C content was relatively in good agreement with that theoretically predicted.

Metastable Ge1–xCx Alloy Nanowires

“…It is known that the incorporated carbon atoms occupy substitutional or interstitial sites in the Ge 1−-x C x alloy system, whereas excess atoms are precipitated onto the surface of the material. 45,46 Substitutional carbon atoms reduce lattice spacing of Ge crystal since the very small covalent radii of carbon atoms induce tensile strain associated with lattice spacing. Thus, band gap could be increased with the carbon concentration at substitutional sites.…”

“…Tunable bandgap energy caused by quantum confinement effect is unique property of nanomaterials and the size reduction to below critical size (e.g., Bohr radius) have shown promising future for optical and electrical application in many papers. , In addition, the bandgap energy can be controlled by lattice-engineered alloy effect which generates appropriate strain between the mixed atoms. It is known that the incorporated carbon atoms occupy substitutional or interstitial sites in the Ge 1–‑ x C x alloy system, whereas excess atoms are precipitated onto the surface of the material. , Substitutional carbon atoms reduce lattice spacing of Ge crystal since the very small covalent radii of carbon atoms induce tensile strain associated with lattice spacing. Thus, band gap could be increased with the carbon concentration at substitutional sites.…”

Chemical Vapour Deposition of CNTs Using Structural Nanoparticle Catalysts

“…This hypothesis is supported by the phase diagram of the Ge-C system presented by Scace & Slack (1959), which indicates that the presence of a small percentage of C has a strong effect in raising the melting point of Ge. Furthermore, Kanazawa et al (2001) demonstrate that Ge 1−y C y alloys can be successfully formed by C implantation into Ge.…”

On the mechanism of carbon nanotube formation: the role of the catalyst

“…This hypothesis is supported by the phase diagram of the Ge-C system presented by Scace and Slack [41], which indicates that the presence of a small percentage of C has a strong effect in raising the melting point of Ge. Furthermore, Kanazawa et al [42] demonstrate that Ge 1−y C y alloys can be successfully formed by C implantation into Ge.…”