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Proceedings Paper

Si0.5Ge0.5 relaxed buffer photodetectors and low-loss polycrystalline silicon waveguides for integrated optical interconnects at L=1.3 um
Author(s): Laura M. Giovane; Ling Liao; Desmond R. Lim; Anuradha Agarwal; Eugene A. Fitzgerald; Lionel C. Kimerling
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Paper Abstract

Silicon based photonic circuits are an attractive option for future generations of microprocessors, if standard VLSI electronics can be coupled with on chip optical interconnects and photodetectors for information transfer and clock distribution. A silicon, VLSI compatible, integrated waveguide-photodetector technology for operation at (lambda) equals 1.3 micrometers is presented. Functionality at 1.3 micrometers permits the use of Si/SiO2 waveguides and offers compatibility with short-haul silica fiber optic systems. These waveguides have a large index contrast ((Delta) n equals 2) thus offering superior optical confinement in strip waveguides with dimensions as small as 0.5 micrometers by 0.2 micrometers . The strong confinement and these small dimensions allow high interconnect line densities without cross-talk or RC delay concerns. We measure optical losses in polysilicon waveguides as low as 13 dB/cm at (lambda) equals 1.3 micrometers using an optical cutback technique. A completely relaxed Si0.5Ge0.5 buffer with low threading dislocation density (approximately 106 cm-2) is used as an epitaxial template for a P-I-N photodetector. The relaxed buffer is grown at 815 degree(s)C with ultra high vacuum chemical vapor deposition using a composition graded layer technique with a grading rate of 10% Ge/micrometers . We measure carrier collection efficiencies of 50% and responsivity of 3 mA/W. A beam propagation model is used to determine an effective absorption length less than 2 micrometers in photodetectors butt- coupled to polySi waveguides.

Paper Details

Date Published: 25 April 1997
PDF: 7 pages
Proc. SPIE 3007, Silicon-Based Monolithic and Hybrid Optoelectronic Devices, (25 April 1997);
Show Author Affiliations
Laura M. Giovane, Massachusetts Institute of Technology (United States)
Ling Liao, Massachusetts Institute of Technology (United States)
Desmond R. Lim, Massachusetts Institute of Technology (United States)
Anuradha Agarwal, Massachusetts Institute of Technology (United States)
Eugene A. Fitzgerald, Massachusetts Institute of Technology (United States)
Lionel C. Kimerling, Massachusetts Institute of Technology (United States)

Published in SPIE Proceedings Vol. 3007:
Silicon-Based Monolithic and Hybrid Optoelectronic Devices
Derek C. Houghton; Bahram Jalali, Editor(s)

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