Novel Si structures for photonic applications

Z. H. Lu, J. M. Baribeau, D. J. Lockwood, M. Buchanan, N. Tit, C. Dharma-wardana, G. C. Aers

Research output: Contribution to journalConference articlepeer-review

16 Citations (Scopus)


Although silicon is the paramount material for the microelectronic industry, bulk Si is of little use for photonic devices owing to its indirect band-gap, which prevents the all-important direct optical transitions. However, a new type of luminescent Si has opened up its future for photonic applications. This new material is light-emitting SiO2/Si superlattices, fabricated in our laboratory. Our theoretical calculations showed that the energy band within the silicon layer has direct bandgap character, a result of strong quantum-confinement caused by the large band-offset at the SiO2/Si interface, so that the direct optical transition is not only possible but also vigorous. For a quantum-confined amorphous silicon, the breakdown of angular momentum will naturally make all optical transition possible. Our experiments have shown that SiO2/Si superlattices can indeed emit bright light. Moreover, the band-gap or the wavelength can be tuned over the visible range by changing the Si layer thickness, in good agreement with quantum confinement theory. The luminescence intensity as a function of Si layer thickness is found to increase, reach a maximum, and then decrease. Theoretical studies show that this phenomena is caused by competition between an increased overlap of electron-hole wave functions in the normal direction to the quantum well and an increased exciton radius in the plane of the quantum well.

Original languageEnglish
Pages (from-to)457-461
Number of pages5
JournalProceedings of SPIE - The International Society for Optical Engineering
Publication statusPublished - 1998
Externally publishedYes
EventProceedings of the 1998 International Conference on Applications of Photonic Technology, ICAPT - Ottawa, Can
Duration: Jul 29 1998Jul 31 1998

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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