Effects of germanium incorporation on optical performances of silicon germanium passive devices for group-IV photonic integrated circuits

Seongjae Cho, Joonsuk Park, Hyungjin Kim, Robert Sinclair, Byung Gook Park, James S. Harris

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Optical interconnect in integrated optoelectronic circuits is one of the promising next-generation technologies for replacing metalized interconnect. Efforts have been made to use silicon (Si)-compatible materials such as germanium (Ge) and Ge-buffered III-V compound semiconductors, along with Si, as optical sources for Si and group-IV integrated optoelectronic systems. This opens the possibility that higher fraction of Ge with its high refractive index (n) can be incorporated in Si waveguide for optical interconnect and the graftability between Si and group-IV or III-V materials would be improved in silicon photonics. In this work, advantageous features of nano-structured silicon germanium (Si1-xGex) optical waveguide with different Ge fraction (x) were evaluated by both optical simulations and theoretical calculations, which are mainly found in the enhanced optical confinement and better interfacing capability. Along with the SiGe waveguide, performance of Si1-xGex microring resonator under material loss in the effect of extinction coefficient (k) has been investigated to suggest the necessity of optimizing the Ge content in Si1-xGe x passive devices. While carrying out the establish design criteria, n and k have been modelled in closed-form functions of Ge fraction at 1550 nm. Furthermore, by examining high-resolution transmission electron microscopy (HR-TEM) images, process compatibility of Ge with either group-IV alloys or III-V compound semiconductors is confirmed for the monolithically integrated photonic circuits.

Original languageEnglish
Pages (from-to)54-68
Number of pages15
JournalPhotonics and Nanostructures - Fundamentals and Applications
Issue number1
StatePublished - Feb 2014

Bibliographical note

Funding Information:
This work was supported by the Centre for Integrated Smart Sensors funded by the Korean Ministry of Science , ICT and Future Planning as Global Frontier Project (CISS-2012M3A6A6054186). Also, the TEM study was supported as part of the Centre on Nanostructuring for Efficient Energy Conversion (CNEEC), an Energy Frontier Research Centre funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001060.


  • Integrated optoelectronic system
  • Material loss
  • Optical interconnect
  • Optical simulation
  • Silicon germanium
  • Transmission electron microscopy


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