Subject: Fwd: EE Ph.D. Oral Examination: Stephanie Claussen, Feb. 10 at 1:00 pm
From: "James W. Conway" <>
Date: Wed, 01 Feb 2012 09:16:28 -0800

-------- Original Message --------
Subject: EE Ph.D. Oral Examination: Stephanie Claussen, Feb. 10 at 1:00 pm
Date: Wed, 1 Feb 2012 09:04:11 -0800
From: Stephanie Claussen <>

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

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.