EE PhD Oral Examination - Rebecca Schaevitz, Thursday, June 2, 2011 at 3:00pm

Rebecca Schaevitz rschaevi at
Wed Jun 1 14:26:36 PDT 2011

Stanford University Oral Defense – Department of Electrical Engineering

Speaker: Rebecca K. Schaevitz

Advisor: Prof. David A. B. Miller

Date: Thursday, June 2, 2011

Time: 3:00 pm (refreshments at 2:45 pm)

Location: Allen-X Auditorium (formerly CIS-X Auditorium) - Room 101


A Simple Quantum Well Electroabsorption Calculator for Germanium Quantum
Well Devices


Germanium is a unique material that is both CMOS-compatible and can be
useful for optoelectronic devices. Leveraging existing CMOS technology, such
as Reduced Pressure Chemical Vapor Deposition (RPCVD), Ge quantum wells are
grown starting on pure Si substrates. The Ge wells exhibit strong
electroabsorption behavior called the quantum-confined Stark effect (QCSE),
which was unexpected in this material when it was first discovered at
Stanford in 2005. With QCSE and Ge, we have the potential to develop highly
CMOS-integrated optoelectronic modulators and bring optical interconnects to
the short computer communication distances. However, given the novelty of
the material system, we need the tools to design future devices that
optimize performance.

In order to create a tool that could allow for future material and device
design, we developed SQWEAC, or the Simple Quantum Well Electroabsorption
Calculator. SQWEAC effectively models the Ge/SiGe quantum well
electroabsorption spectra using simple physical models. The use of simple
models drastically speeds up the computation time compared to more common
methods like k.p and tight-binding. In this presentation, I will describe
SQWEAC and show its effectiveness in modeling current Ge quantum well
material. I will also present future modulator device concepts that could
meet the strict criteria of power, size, extinction ratio and insertion
loss, and allow us to bring optical interconnects to the chip level.
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