Direct bandgap germanium-on-silicon inferred from 57% 〈100〉 uniaxial tensile strain [Invited]

Sukhdeo, David S.; Nam, Donguk; Kang, Ju-Hyung; Brongersma, Mark L.; Saraswat, Krishna C.

doi:10.1364/prj.2.0000a8

Cited by 151 publications

(141 citation statements)

References 26 publications

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“…Great efforts have been made to modify these materials, e.g. by applying tensile strain and/or by forming alloys, [16][17][18][19] in order to obtain a direct band gap. Here, Ge plays an essential role, since the energy difference between the conduction band -valley at the center of the Brillouin zone and the L-valleys, the energetically lowest conduction bands, is only 140 meV.…”

Section: Introductionmentioning

confidence: 99%

Optically Pumped GeSn Microdisk Lasers on Si

et al. 2016

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The strong correlation between advancing the performance of Si microelectronics and their demand of low power consumption requires new ways of data communication. Photonic circuits on Si are already highly developed except for an eligible on-chip laser source integrated monolithically. The recent demonstration of an optically pumped waveguide laser made from the Si-congruent GeSn alloy, monolithical laser integration has taken a big step forward on the way to an all-inclusive nanophotonic platform in CMOS. We present group IV microdisk lasers with significant improvements in lasing temperature and lasing threshold compared to the previously reported nonundercut Fabry−Perot type lasers. Lasing is observed up to 130 K with optical excitation density threshold of 220 kW/cm 2 at 50 K. Additionally the influence of strain relaxation on the band structure of undercut resonators is discussed and allows the proof of laser emission for a just direct Ge 0.915 Sn 0.085 alloy where Γ and L valleys have the same energies. Moreover, the observed cavity modes are identified and modeled.

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Section: Introductionmentioning

confidence: 99%

Optically Pumped GeSn Microdisk Lasers on Si

et al. 2016

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“…While this strain can be a useful starting point, it is not enough to reduce threshold current density to a practical level. Other methods include depositing nitride stressor layers [16][17][18][19], suspending silicon dioxide and then transferring the strain into Ge micro disks [20,21] and suspending Germanium directly (the focus of this paper) [22][23][24][25][26][27][28][29][30].Suspended structures amplify the small amounts of tensile biaxial strain introduced during the epitaxial growth of Ge on Si. Certain regions of the Ge are suspended in which the membrane constricts resulting in an enhancement of the tensile strain, and the regions which are still tethered to the rest of the wafer (referred to as pads) relax resulting in a compressive strain.…”

Section: Introductionmentioning

confidence: 99%

Enhanced light emission from improved homogeneity in biaxially suspended Germanium membranes from curvature optimization

Burt¹,

Al-Attili²,

Zuo³

et al. 2017

Opt. Express

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A silicon compatible light source is crucial to develop a fully monolithic silicon photonics platform. Strain engineering in suspended Germanium membranes has offered a potential route for such a light source. However, biaxial structures have suffered from poor optical properties due to unfavorable strain distributions. Using a novel geometric approach and finite element modelling (FEM) structures with improved strain homogeneity were designed and fabricated. Micro-Raman (μ-Raman) spectroscopy was used to determine central strain values. Micro-photoluminescence (μ-PL) was used to study the effects of the strain profiles on light emission; we report a PL enhancement of up to 3x by optimizing curvature at a strain value of 0.5% biaxial strain. This geometric approach offers opportunity for enhancing the light emission in Germanium towards developing a practical on chip light source.© 2017 Optical Society of America OCIS codes: (220.0220) Optical design and fabrication; (250.0250) Optoelectronics. References and links1. D. A. B. Miller, "Rationale and challenges for optical interconnects to electronic chips," Proc. IEEE 88(6), 728-749 (2000). 2. R. Soref, "Mid-infrared photonics in silicon and germanium," Nat. Photonics 4(8), 495-497 (2010).

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“…Ge, an indirect bandgap semiconductor, highly compatible with Si technology, has been predicted to exhibit a direct gap under high tensile strain (Zhang & Crespi, 2009), and various fabrication approaches have been proposed (Sun et al, 2009;Sü ess et al, 2013;Sukhdeo et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Structural investigations of the α₁₂Si–Ge superstructure

et al. 2015

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This article reports the X-ray diffraction-based structural characterization of the α12multilayer structure SiGe2Si2Ge2SiGe12[d'Avezac, Luo, Chanier & Zunger (2012).Phys. Rev. Lett.108, 027401], which is predicted to form a direct bandgap material. In particular, structural parameters of the superlattice such as thickness and composition as well as interface properties, are obtained. Moreover, it is found that Ge subsequently segregates into layers. These findings are used as input parameters for band structure calculations. It is shown that the direct bandgap properties depend very sensitively on deviations from the nominal structure, and only almost perfect structures can actually yield a direct bandgap. Photoluminescence emission possibly stemming from the superlattice structure is observed.

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Direct bandgap germanium-on-silicon inferred from 57% 〈100〉 uniaxial tensile strain [Invited]

Cited by 151 publications

References 26 publications

Optically Pumped GeSn Microdisk Lasers on Si

Optically Pumped GeSn Microdisk Lasers on Si

Enhanced light emission from improved homogeneity in biaxially suspended Germanium membranes from curvature optimization

Structural investigations of the α₁₂Si–Ge superstructure

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Direct bandgap germanium-on-silicon inferred from 57% 〈100〉 uniaxial tensile strain [Invited]

Cited by 151 publications

References 26 publications

Optically Pumped GeSn Microdisk Lasers on Si

Optically Pumped GeSn Microdisk Lasers on Si

Enhanced light emission from improved homogeneity in biaxially suspended Germanium membranes from curvature optimization

Structural investigations of the α12Si–Ge superstructure

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Structural investigations of the α₁₂Si–Ge superstructure