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

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

Title

A Simple Quantum Well Electroabsorption Calculator for the Germanium Material System

Abstract

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.