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Nanomaterials 2018, 8(6), 407;

Optical Properties of Tensilely Strained Ge Nanomembranes

Department of Electrical and Computer Engineering and Photonics Center, Boston University, Boston, MA 02215, USA
Department of Materials Science and Engineering, University of Wisconsin, Madison, WI 53706, USA
Author to whom correspondence should be addressed.
Received: 16 April 2018 / Revised: 30 May 2018 / Accepted: 4 June 2018 / Published: 6 June 2018
(This article belongs to the Special Issue Silicon-Based Nanomaterials: Technology and Applications)
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Group-IV semiconductors, which provide the leading materials platform of micro- electronics, are generally unsuitable for light emitting device applications because of their indirect- bandgap nature. This property currently limits the large-scale integration of electronic and photonic functionalities on Si chips. The introduction of tensile strain in Ge, which has the effect of lowering the direct conduction-band minimum relative to the indirect valleys, is a promising approach to address this challenge. Here we review recent work focused on the basic science and technology of mechanically stressed Ge nanomembranes, i.e., single-crystal sheets with thicknesses of a few tens of nanometers, which can sustain particularly large strain levels before the onset of plastic deformation. These nanomaterials have been employed to demonstrate large strain-enhanced photoluminescence, population inversion under optical pumping, and the formation of direct-bandgap Ge. Furthermore, Si-based photonic-crystal cavities have been developed that can be combined with these Ge nanomembranes without limiting their mechanical flexibility. These results highlight the potential of strained Ge as a CMOS-compatible laser material, and more in general the promise of nanomembrane strain engineering for novel device technologies. View Full-Text
Keywords: nanomembranes; optical gain media; group-IV semiconductors; strain engineering nanomembranes; optical gain media; group-IV semiconductors; strain engineering

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Paiella, R.; Lagally, M.G. Optical Properties of Tensilely Strained Ge Nanomembranes. Nanomaterials 2018, 8, 407.

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