Low-temperature (≤300°C) formation of orientation-controlled large-grain (≥10μm) Ge-rich SiGe on insulator by gold-induced crystallization

• Published in: Thin solid films 2016-03, Vol.602, p.3-6
• Main Authors: Sadoh, T., Park, J.-H., Aoki, R., Miyao, M.
• Format: Article
• Language: English
• Subjects: Annealing; Crystal structure; Electronics; Flexible electronics; Formations; Germanium; Insulators; Metal-induced crystallization; Silicon dioxide; Silicon germanides; Silicon germanium; Thin-film transistor
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2015.10.057

Low-temperature (≤300°C) formation of orientation-controlled large-grain (≥10μm) Ge-rich (≥50%) SiGe crystals on insulator are realized by the gold-induced layer-exchange technique. Stacked structures of a-Si1−xGex (0≤x≤1)/Au/SiO2 are employed as starting materials. Here, thin-Al2O3 layers are introduced as diffusion barrier at a-SiGe/Au interfaces to suppress random bulk-nucleation and make (111)-oriented interface-nucleation on SiO2 dominant. For samples with Ge fraction of 80%–100%, (111)-oriented large-grains (≥10μm) are obtained through layer-exchange during annealing at 250°C. On the other hand, layer-exchange for Ge fraction of 50% does not proceed at 250°C. This phenomenon is attributed to retardation of lateral growth by introduction of Si. To enhance lateral growth, increase of annealing temperature is examined. As a result, (111)-oriented large-grains (≥10μm) are realized for SiGe with Ge fraction of 50%–100%, having uniform composition profiles, by annealing at 300°C. This technique is very useful to realize high-performance flexible electronics, employing plastic substrates (softening temperature: ~350°C). •Gold-induced crystallization is developed to Ge-rich SiGe on insulator.•Layer-exchange crystallization proceeds at low temperatures (≤300°C).•(111)-oriented large-grain (≥10μm) SiGe is realized for Ge fraction of 50%–100%.