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Photonics 2014, 1(3), 162-197; doi:10.3390/photonics1030162

Monolithically Integrated Ge-on-Si Active Photonics

Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755, USA
Received: 27 May 2014 / Revised: 19 June 2014 / Accepted: 19 June 2014 / Published: 2 July 2014
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Monolithically integrated, active photonic devices on Si are key components in Si-based large-scale electronic-photonic integration for future generations of high-performance, low-power computation and communication systems. Ge has become an interesting candidate for active photonic devices in Si photonics due to its pseudo-direct gap behavior and compatibility with Si complementary metal oxide semiconductor (CMOS) processing. In this paper, we present a review of the recent progress in Ge-on-Si active photonics materials and devices for photon detection, modulation, and generation. We first discuss the band engineering of Ge using tensile strain, n-type doping, Sn alloying, and separate confinement of Γ vs. L electrons in quantum well (QW) structures to transform the material towards a direct band gap semiconductor for enhancing optoelectronic properties. We then give a brief overview of epitaxial Ge-on-Si materials growth, followed by a summary of recent investigations towards low-temperature, direct growth of high crystallinity Ge and GeSn alloys on dielectric layers for 3D photonic integration. Finally, we review the most recent studies on waveguide-integrated Ge-on-Si photodetectors (PDs), electroabsorption modulators (EAMs), and laser diodes (LDs), and suggest possible future research directions for large-scale monolithic electronic-photonic integrated circuits on a Si platform.
Keywords: Ge; GeSi; GeSn; tensile strain; band engineering; integrated silicon photonics; optoelectronics; photodetectors; modulators; lasers Ge; GeSi; GeSn; tensile strain; band engineering; integrated silicon photonics; optoelectronics; photodetectors; modulators; lasers
This is an open access article distributed under the Creative Commons Attribution License (CC BY) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Liu, J. Monolithically Integrated Ge-on-Si Active Photonics. Photonics 2014, 1, 162-197.

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