Strained germanium technology for on-chip optical interconnects
Abstract/Contents
- Abstract
- Since the invention of the first transistor over half a century ago, transistor scaling has led the semiconductor industry to blossom. Despite the improved performance of scaled transistors, however, the computational speed of integrated circuits (IC) has now become limited by their electrical interconnects. To alleviate this performance bottleneck in ICs, optical interconnects, which have already revolutionized long-haul communications, have recently gained much attention for on-chip applications. Over the past decade many of the key constituents of an on-chip optical interconnect system, such as high-performance photodetectors and modulators, have been demonstrated on a silicon-compatible platform. However, an efficient light source remains particularly challenging: silicon and silicon-compatible materials such as germanium (Ge) are not readily suitable for light emission because their band gaps are indirect. It has been proposed to use tensile strain to make Ge's band gap direct and therefore suitable for light emission, however experimental realization has thus far been lacking. In this dissertation, we focus on developing an efficient silicon-compatible light emitter based on strained Ge technology. Starting from theoretical calculations showing how tensile strain can improve the light emission efficiency of Ge, we present several approaches for enhancing light emission from highly strained Ge on a CMOS-compatible platform. In the first part, we describe a thin film membrane technique in which a large residual stress in a tungsten layer is used as a stressor to induce a biaxial strain in a Ge membrane, upon which we have fabricated optoelectronic devices. In the second part, we introduce an approach to induce uniaxial strain that can potentially create a direct band gap in Ge wire using geometrical amplification of a small pre-existing strain. Lastly, we present a novel way to mimic double-heterostructure behavior within a single material, further enhancing light emission from Ge by capturing photo-generated carriers within a strain-induced potential well. Throughout this dissertation, we discuss the implications of these experimental achievements towards creating an efficient Ge laser for use in silicon-compatible optical interconnects.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2013 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Nam, Donguk |
|---|---|
| Associated with | Stanford University, Department of Electrical Engineering. |
| Primary advisor | Saraswat, Krishna |
| Thesis advisor | Saraswat, Krishna |
| Thesis advisor | Brongersma, Mark L |
| Thesis advisor | Harris, J. S. (James Stewart), 1942- |
| Advisor | Brongersma, Mark L |
| Advisor | Harris, J. S. (James Stewart), 1942- |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Donguk Nam. |
|---|---|
| Note | Submitted to the Department of Electrical Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2013. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2013 by Donguk Nam
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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