Publication # 336

336.   O. Fidaner, A. K. Okyay, J. E. Roth, R. K. Schaevitz, Y.-H. Kuo, K. C. Saraswat, J. S. Harris, Jr., and D. A. B. Miller, "Ge-SiGe Quantum-Well Waveguide Photodetectors on Silicon for the Near-Infrared," IEEE Photonics Technol. Lett. 19, 1631 – 1633 (2007)

We demonstrate near-infrared waveguide photodetectors using Ge/SiGe quantum wells epitaxially grown on a silicon substrate.  The diodes exhibit a low dark current of 17.9 mA/cm² at 5 V reverse bias.  The photodetectors are designed to work optimally at ~1480 nm, where the external responsivity is 170 mA/W, which is mainly limited by the fiber-to-waveguide coupling loss.  The ~1480 nm wavelength matches the optimum wavelength for quantum-well electroabsorption modulators built on the same epitaxy, but these photodetectors also exhibit performance comparable to the demonstrated Ge-based detectors at longer wavelengths.  At 1530 nm, we see open eye diagrams at 2.5 Gb/s operation and the external responsivity is as high as 66 mA/W.  The technology is potentially integrable with the standard CMOS process and offers an efficient solution for on-chip optical interconnects.

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