Effects of carbon coverage on Ge quantum dots formation on Si(100) using C-Si reaction and transition of Ge growth mode

Kosuke Yasuta, Yuhki Itoh, Tomoyuki Kawashima, Katsuyoshi Washio

Research output: Contribution to journalArticlepeer-review

Abstract

Effects of carbon (C) coverage on C-mediated Ge quantum dots (QDs) formation on a Si(100) substrate changing a state of surface reconstruction were investigated by using solid-source molecular beam epitaxy. For C=0–2.0 monolayers (MLs), the Ge QD scaled down and its density increased with C coverage. In addition, growth mode of Ge QDs changed from Volmer-Weber (VW) mode without a wetting layer to Stranski-Krastanov (SK) mode with the wetting layer for C=0.50–0.75 ML. This transition was induced by decrease in interfacial energy between Ge and Si surface due to the formation of C-Ge bonds near the Ge/Si interface. For C≥2.5 MLs, the Ge QD enlarged slightly and its density decreased with increasing C coverage, and he Ge growth mode went back to the VW mode. The Raman spectroscopy and X-ray photoelectron spectroscopy revealed the formation of a mixture of amorphous C and nano-crystalline graphite on the Si surface. Thus, the formation of a large amount of C–C (sp2) bonds induced the growth transition of QDs from the SK mode to the VW mode due to the decrease in surface energy of C.

Original languageEnglish
Pages (from-to)173-177
Number of pages5
JournalMaterials Science in Semiconductor Processing
Volume70
DOIs
Publication statusPublished - 2017 Nov 1

Keywords

  • Carbon
  • Germanium
  • Molecular beam epitaxy (MBE)
  • Quantum dots
  • Silicon
  • X-ray photoelectron spectroscopy

ASJC Scopus subject areas

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

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