Formation and Strain Analysis of Stacked Ge Quantum Dots With Strain-Compensating Si1−xCx Spacer

Yuhki Itoh, Tomoyuki Kawashima, Katsuyoshi Washio

Research output: Contribution to journalArticlepeer-review

Abstract

To stack Ge quantum dots (QDs) in a multilayer structure without undesirable enlargement of the QDs, the effects of both Si1−xCx spacer on a strain compensation of the embedded QDs and a sub-monolayer (ML) carbon (C) mediation on a formation of the Volmer-Weber (VW)-mode Ge QDs on the Si1−xCx spacer were investigated. In a Si1−xCx/Ge/Si(100) structure, lattice rexation of the embedded QDs was kept about 80% at x = 0.015. This maintaining the state of high relaxation attributed to a tensile strain from the Si1−xCx layer grown on a surface of a Si substrate around the QDs. In addition, by utilizing an analysis of Kelvin probe force microscopy, it was revealed that the sub-ML C mediation of 0.25 ML and over is effective to form the VW-mode Ge QDs on the Si1−xCx spacer. This is because the promotion of subdivision effect for the formation of the QDs via C mediation was also effective on the Si1−xCx surface. At C = 0.25 and 0.5 ML, diameter and density of second QDs were about 22 nm and 1.5 × 1011cm−2, respectively. These results pave the way to stack the VW-mode Ge QDs in the multilayer structure without enlargement of the QDs.

Original languageEnglish
Article number1700197
JournalPhysica Status Solidi (C) Current Topics in Solid State Physics
Volume14
Issue number12
DOIs
Publication statusPublished - 2017 Dec

Keywords

  • epitaxial growth
  • germanium
  • group-IV semiconductor
  • quantum dots
  • strain compensation

ASJC Scopus subject areas

  • Condensed Matter Physics

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