Strain modification in thin Si1-x-yGexCy alloys on (100) Si for formation of high density and uniformly sized quantum dots

Xiaoping Shao, Ralf Jonczyk, M. Dashiell, D. Hits, B. A. Orner, A. S. Khan, K. Roe, J. Kolodzey, Paul R. Berger, M. Kaba, M. A. Barteau, K. M. Unruh

Research output: Contribution to journalArticleScientificpeer-review

9 Citations (Scopus)

Abstract

The effects of alloying C with Ge and Si and varying the C/Ge ratio during the growth of very thin layers of the ternary alloy SiGeC grown on Si (100) substrates and the resulting strain modification on self-assembled and self-organized quantum dots are examined. During coherent islanded growth, where dislocations are not formed yet to relieve the strain, higher strain energy produced by greater lattice mismatch acts to reduce the island size, increase the density of islands, and significantly narrow the distribution of island sizes to nearly uniformly sized quantum dots. Strain energy can also control the critical thickness for dislocation generation within the three-dimensional islands, which then limits the maximum height which coherent islands can achieve. After the islands relax by misfit dislocations, the island sizes increase and the island size distribution becomes broader with the increase of misfit and strain. The optimal growth for a high density of uniform coherent islands occurred for the Si0.49Ge0.48C0.03 alloy composition grown on (100) Si, at a growth temperature of 600°C, with an average thickness of 5 nm, resulting in a narrow size distribution (about 42 nm diameter) and high density (about 2×1010dots/cm2) of quantum dots.

Original languageEnglish
Pages (from-to)578-582
Number of pages5
JournalJournal of Applied Physics
Volume85
Issue number1
DOIs
Publication statusPublished - 1999
Externally publishedYes
Publication typeA1 Journal article-refereed

ASJC Scopus subject areas

  • General Physics and Astronomy

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