Novel Si  structures for photonic applications

Z. H. Lu; J.-M. Barubeau; David J. Lockwood; Margaret Buchanan; Nacir Tit; C. Dharma-Wardana; Geof C. Aers

doi:10.1117/12.328772

4 December 1998 Novel Si structures for photonic applications

Z. H. Lu, J.-M. Barubeau, David J. Lockwood, Margaret Buchanan, Nacir Tit, C. Dharma-Wardana, Geof C. Aers

Proceedings Volume 3491, 1998 International Conference on Applications of Photonic Technology III: Closing the Gap between Theory, Development, and Applications; (1998) https://doi.org/10.1117/12.328772
Event: 1998 International Conference on Applications of Photonic Technology, 1998, Ottawa, Canada

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.

Citation Download Citation

Z. H. Lu, J.-M. Barubeau, David J. Lockwood, Margaret Buchanan, Nacir Tit, C. Dharma-Wardana, and Geof C. Aers "Novel Si structures for photonic applications", Proc. SPIE 3491, 1998 International Conference on Applications of Photonic Technology III: Closing the Gap between Theory, Development, and Applications, (4 December 1998); https://doi.org/10.1117/12.328772

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