EE Ph.D. Oral Examination: Stephanie Claussen, Feb. 10 at 1:00 pm

Stephanie Claussen sclaussen at
Wed Feb 1 09:04:11 PST 2012

Stanford University Ph.D. Oral Examination – Department of Electrical

Speaker: Stephanie Claussen
Advisor: Professor David A. B. Miller
Date: Friday, February 10, 2012
Time: 1:00 pm (refreshments at 12:45 pm)
Location: Allen-X Auditorium (formerly CIS-X Auditorium) - Room 101

High-performance Ge/SiGe quantum well waveguide modulators for optical
interconnect systems

Electrical interconnects are rapidly nearing fundamental density-related
and energy consumption limitations. Scaling a wire down in size does not
allow it to carry more information, and the associated power consumption is
becoming environmentally-significant. Optical interconnects provide a
promising solution, but require CMOS-compatible, high-speed, low-energy
optical components in order to be feasible. Ge/SiGe quantum wells (QWs)
exhibit the quantum-confined Stark effect, a strong electroabsorption
mechanism that enables compact optical modulators for use in future optical
interconnect systems.

To design and optimize high-performance modulators, we have experimentally
investigated the ultrafast carrier dynamics and transport properties of
Ge/SiGe QWs. We discuss the implications of these measured femtosecond
carrier lifetimes on the ultimate performance limitations of these devices.

We will then present recent progress toward achieving Ge/SiGe QW modulators
integrated with low-loss silicon-on-insulator (SOI) waveguides. Waveguide
modulators enable easy integration with other interconnect components and
potentially high modulation contrast ratios. However, integration with SOI
waveguides requires controllable selective-area epitaxial growth of the QW
material. In this talk, we show demonstrations of high-quality
selective-area growth of Ge and SiGe and discuss our advancements in the
fabrication of Ge/SiGe QW waveguide modulators.
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