Sn-alloying as a means of increasing the optical absorption of Ge at the C- and L-telecommunication bands

Vijay R. D'Costa, Yanyan Fang, Jay Mathews, Radek Roucka, John Tolle, Jose Menendez, John Kouvetakis

Research output: Contribution to journalArticle

85 Scopus citations

Abstract

The optical properties of Ge1-ySny alloys (y ∼ 0.02) grown by chemical vapor deposition on Si substrates have been studied using spectroscopic ellipsometry and photocurrent spectroscopy. The system shows a 10-fold increase in optical absorption, relative to pure Ge, at wavelengths corresponding to the C-telecommunication band (1550 nm) and a 20-fold increase at wavelengths corresponding to the L-band (1620 nm). Measurements on a series of samples with different thicknesses reveal nearly identical dielectric functions, from which the composition reproducibility of the growth method is estimated to be as good as 0.1%. It is shown that a model that includes excitonic effects reproduces the measured onset of absorption using the direct band gap E0 as essentially the only adjustable parameter of the fit.

Original languageEnglish (US)
Article number115006
JournalSemiconductor Science and Technology
Volume24
Issue number11
DOIs
StatePublished - Nov 25 2009

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering
  • Materials Chemistry

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