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Proceedings Paper

Novel Si structures for photonic applications
Author(s): Z. H. Lu; J.-M. Barubeau; David J. Lockwood; Margaret Buchanan; Nacir Tit; C. Dharma-Wardana; Geof C. Aers
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Paper Abstract

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.

Paper Details

Date Published: 4 December 1998
PDF: 5 pages
Proc. SPIE 3491, 1998 International Conference on Applications of Photonic Technology III: Closing the Gap between Theory, Development, and Applications, (4 December 1998); doi: 10.1117/12.328772
Show Author Affiliations
Z. H. Lu, National Research Council Canada (Canada)
J.-M. Barubeau, National Research Council Canada (Canada)
David J. Lockwood, National Research Council Canada (Canada)
Margaret Buchanan, National Research Council Canada (Canada)
Nacir Tit, National Research Council Canada (Canada)
C. Dharma-Wardana, National Research Council Canada (Canada)
Geof C. Aers, National Research Council Canada (Canada)

Published in SPIE Proceedings Vol. 3491:
1998 International Conference on Applications of Photonic Technology III: Closing the Gap between Theory, Development, and Applications
George A. Lampropoulos; Roger A. Lessard, Editor(s)

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