Influence of crystallinity of as-deposited Ge film on formation of quantum dot in carbon-mediated solid-phase epitaxy

Kaito Takeshima, Yuhki Itoh, Tomoyuki Kawashima, Katsuyoshi Washio

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

The influence of crystallinity of as-deposited Ge films on Ge quantum dot (QD) formation via carbon (C)-mediated solid-phase epitaxy (SPE) was investigated. The samples were fabricated by solid-source molecular beam epitaxy (MBE). Ge/C/Si structure was formed by sequential deposition of C and Ge at deposition temperature (TD) of 150–400 °C, and it was heat-treated in the MBE chamber at 650 °C. In the case of amorphous or a mixture of amorphous and nano-crystalline Ge film grown for TD ≤250 °C, density of QDs increased with increasing TD due to the increase of C-Ge bonds in Ge layer. Ge QDs with diameter of 9.2±2.1 nm were formed in the highest density of 8.3×1011 cm−2 for TD =250 °C. On the contrary, in the case of polycrystalline Ge film for TD ≥300 °C, density of QDs decreased slightly. This is because C incorporation into Ge layer during SPE was suppressed due to the as-crystallized columnar grains. These results suggest that as-deposited Ge film in a mixture of amorphous and nano-crystalline state is suitable to form small and dense Ge QDs via C-mediated SPE.

Original languageEnglish
Pages (from-to)178-182
Number of pages5
JournalMaterials Science in Semiconductor Processing
Volume70
DOIs
Publication statusPublished - 2017 Nov 1

Keywords

  • Carbon
  • Germanium
  • Molecular beam epitaxy (MBE)
  • Quantum dot
  • Silicon
  • Solid-phase epitaxy

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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