Silicon-nanocrystal Optoelectronic Kerr Effect for Complementary Metal-oxide Semiconductor (CMOS) Compatible Optical Switching

Report No. ARL-TR-5514
Authors: Neal K. Bambha, Justin R. Bickford, and Stefan F. Preble
Date/Pages: April 2011; 18 pages
Abstract: There is a broad Army need to quickly transfer large amounts of data from sensors to processors on a wide variety of systems. Complementary metal-oxide semiconductor (CMOS) compatible optical intra-chip data communication systems would enable this data flow by increasing data rates and reducing circuit size and power. We investigated the fabrication of a monolithic CMOS-compatible optoelectronic silicon (Si) modulator for intra-chip communication. The modulator is designed to take advantage of the large Kerr effect that has been reported in Si-nanocrystals imbedded in oxide (Si-nc). The expected refractive index change versus applied voltage was calculated for the design, and an index change of ~2 x 10-4 is enough to modulate the light, corresponding to a voltage of only 0.5-1.5 V. Confinement of light in the waveguide and microdisk is accomplished via a slot waveguide design. Several samples of Si-rich oxide films were deposited by reactively sputtering Si in the presence of oxygen, plasma enhanced chemical vapor deposition (PECVD), and low pressure chemical vapor deposition (LPCVD), as well as spin casting of hydrogen silsesquioxane (HSQ). The nonlinear index of these samples was characterized by an optical Zscan measurement using a short pulse fiber laser with a 1.5-μm wavelength.
Distribution: Approved for public release
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Last Update / Reviewed: April 1, 2011