Interfacial abruptness in Si/SiGe heteroepitaxy grown by ultrahigh vacuum chemical vapor deposition

Wen Chung Tsai*, Chun Yen Chang, Tz Guei Jung, Ting Chang Chang, Horng-Chih Lin, Liang Po Chen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

High-quality Si/Si1-xGex strained-layer superlattices have been grown in the temperature range 525°C-550°C by ultrahigh vacuum chemical vapor deposition. We employed X-ray reflection and high-resolution double-crystal X-ray diffraction measurements to study the dimensional and compositional variations in a Si/Si1-xGex superlattice. From the X-ray reflection results, the interfacial roughness of Si layers on SiGe, and SiGe layers on Si, is 0.1 nm for growth at 525°C and 0.2 nm for growth at 550°C. A simple model for estimating the interfacial abruptness of Si/Si1-xGex heterojunctions is proposed. In this model, a transition region with a linearly graded Ge composition is assumed to exist at both Si/Si1-xGex interfaces. The Ge composition x of a Si/Si1-xGex superlattice is found to increase with the growth time at a constant gas phase composition. This phenomenon can be explained by this model, and the thickness of the transition region and the transition time can be extracted from these fitting results. The transition thicknesses are found to be about 0.3-0.7 nm for growth at 525°C and 1-1.5 nm for growth at 550°C.

Original languageEnglish
Pages (from-to)5680-5687
Number of pages8
JournalJapanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Volume36
Issue number9 A
DOIs
StatePublished - 1 Sep 1997

Keywords

  • Abruptness
  • Heteroepitaxy
  • Roughness
  • Superlattice
  • X-ray reflection

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