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Si-based GeSn lasers with wavelength coverage of 2 to 3 µm and operating temperatures up to 180 K Joe margetis, Sattar Al-Kabi, Wei Du, Wei Dou, Yiyin Zhou, Thach Pham, Perry Grant, Seyed Ghetmiri, Aboozar Mosleh, Baohua Li, Jifeng Liu, Greg Sun, Richard Soref, John Tolle, Mansour Mortazavi, and Shui-Qing Yu ACS Photonics, Just Accepted Manuscript • DOI: 10.1021/acsphotonics.7b00938 • Publication Date (Web): 15 Dec 2017 Downloaded from http://pubs.acs.org on December 16, 2017
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ACS Photonics
Si-based GeSn lasers with wavelength coverage of 2 to 3 µm and operating temperatures up to 180 K Joe Margetis1*, Sattar Al-Kabi2*, Wei Du3,4, Wei Dou2, Yiyin Zhou2,5, Thach Pham2,5, Perry Grant2,5, Seyed Ghetmiri2, Aboozar Mosleh2, Baohua Li5, Jifeng Liu6, Greg Sun7, Richard Soref7, John Tolle1, Mansour Mortazavi3, Shui-Qing Yu2† 1
ASM, 3440 East University Drive, Phoenix, Arizona 85034, USA
2
Department of Electrical Engineering, University of Arkansas, Fayetteville, Arkansas 72701
USA 3
Department of chemistry and Physics, University of Arkansas at Pine Bluff, Pine Bluff,
Arkansas 71601 USA 4
Department of Electrical Engineering, Wilkes University, Wilkes-Barre, Pennsylvania 18766
USA 5
Arktonics, LLC. 1339 South Pinnacle Drive, Fayetteville, Arkansas 72701 USA
6
Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755 USA
7
Department of Engineering, University of Massachusetts Boston, Boston, Massachusetts 02125
USA.
*These authors contributed equally to this work. †
Corresponding author.
Abstract A Si-based monolithic laser is strongly desired for the full integration of Si-photonics. Lasing from the direct bandgap group-IV GeSn alloy has opened a new avenue, different from the hybrid III-V-on-Si integration approach. We demonstrated optically pumped GeSn lasers on Si with broad wavelength coverage from 2 to 3 µm. The GeSn alloys were grown using newly developed approaches with an industry standard chemical vapor deposition reactor and low-cost commercially available precursors. The achieved maximum Sn composition of 17.5% exceeded the generally acknowledged Sn incorporation limits found with similar deposition chemistries. The highest lasing temperature was measured as 180 K with the active layer thickness as thin as 1 ACS Paragon Plus Environment
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260 nm. The unprecedented lasing performance is mainly due to the unique growth approaches, which offer high-quality epitaxial materials. The results reported in this work show a major advance towards Si-based mid-infrared laser sources for integrated photonics. Keywords: GeSn, infrared laser, Si photonics
The Si-based electronics industry has driven the digital revolution for unprecedented success. As a result, there have been tremendous efforts to broaden the reach of Si technology to build integrated photonics1-3.
Although great success has been made on Si-based waveguides4,
modulators5, and photodetectors6,7, a monolithic integrated light source on Si with high efficiency and reliability remains missing and is seen as the most challenging task to form a complete set of Si-photonic components. Currently, Si photonics utilizes direct bandgap III-V lasers as the light source through different integration approaches such as wafer-bonding or direct-growth, which has seen significant progress in the last decade8-11.
The effort on
developing GeSn lasers is motivated mainly by the possibility of attaining monolithic laser sources integrated on Si. Although the bandgaps of the GeSn system indicate that the telecom wavelengths of 1.3 and 1.55 µm are beyond reach, the longer wavelength range around 2 µm and beyond where this material system thrives are still very important and highly relevant for a variety of applications such as gas sensing, infrared imaging, etc. From the other side, a laser made from direct bandgap group-IV materials offers its own unique advantages, particularly the material integration compatibility with the complementary metal–oxide–semiconductor (CMOS) process. However, group-IV materials such as Si, Ge, and SiGe alloys have been excluded from being an efficient light source due to their indirect bandgap nature. Although the optically pumped Er doped Si laser12 and the Si Raman laser13 have been reported, they do not rely on bandgap emission and cannot be operated under direct electrical pumping. Recently developed
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ACS Photonics
Ge lasers14-16 employed strain-engineering and heavy n-type doping to compensate for the indirect bandgap, yet the high threshold and fabrication difficulties remain unresolved thus far. It has been theoretically predicted that the group-IV alloy GeSn could achieve a direct bandgap by incorporating more than 6-10% Sn into Ge17-19. In order to overcome the limit of low solid solubility of Sn in Ge (
