Disentangling nonradiative recombination processes in Ge micro-crystals on Si substrates

Pezzoli, Fabio; Giorgioni, A; Gallacher, Kevin; Isa, Fabio; Biagioni, Paolo; Millar, Ross W.; Gatti, E.; Grilli, E.; Bonera, Emiliano; Isella, Giovanni; Paul, Douglas J.; Miglio, Leo

doi:10.1063/1.4955020

Cited by 18 publications

(14 citation statements)

References 34 publications

(53 reference statements)

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“…This distinct PL behavior would have been otherwise concealed by the presence of nonradiative recombination channels opened up by dislocations. Such extended defects are introduced in the Ge 1-x Sn x epitaxial layers through plastic strain relaxation and are known to trigger 5 a Schön-Klasens-like recombination dynamics, which, as opposed to the present case, enhances the PL intensity in the high temperature regime 43,[48][49][50] .…”

Section: Optical Features Of Pseudomorphic Ge 1-x Sn Xmentioning

confidence: 77%

“…1). Fig 3b summarizes Since the band-to-band recombination pertaining to indirect gap materials develops on a slower time scale 7,48 , we attribute the measured temperature dependence of the lifetime to the presence of extrinsic recombination channels defined by shallow (13-17 meV) energy levels (see Supplementary Note 1 for a detailed discussion). Such scenario compares satisfactorily with the temperature-induced quenching of the PL obtained under steady state conditions and summarized in Fig.…”

Section: Optical Features Of Pseudomorphic Ge 1-x Sn Xmentioning

confidence: 99%

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Spin-coherent dynamics and carrier lifetime in strained Ge1−xSnx semiconductors on silicon

et al. 2019

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Germanium-Tin is emerging as a material exhibiting excellent photonic properties. Here we demonstrate optical initialization and readout of spins in this intriguing group IV semiconductor alloy and report on spin quantum beats between Zeeman-split levels under an external magnetic field. Our optical experiments reveal robust spin orientation in a wide temperature range and a persistent spin lifetime that approaches the ns regime at room temperature. Besides important insights into nonradiative recombination pathways, our findings disclose a rich spin physics in novel epitaxial structures directly grown on a conventional Si substrate. This introduces a viable route towards the synergic enrichment of the group IV semiconductor toolbox with advanced spintronics and photonic capabilities.

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Section: Optical Features Of Pseudomorphic Ge 1-x Sn Xmentioning

confidence: 77%

Section: Optical Features Of Pseudomorphic Ge 1-x Sn Xmentioning

confidence: 99%

Spin-coherent dynamics and carrier lifetime in strained Ge1−xSnx semiconductors on silicon

et al. 2019

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“…Both maximum operating temperatures are higher than that of the reported GeSn micro-disk lasers 25 (130 K) and ridge waveguide lasers (110 K). 24 We attribute the superior laser performance to the high-quality materials that were grown via unique approaches, and to the significant reduction of the modal overlap with the misfit dislocations localized at the Ge/GeSn interface 32 .…”

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confidence: 99%

Si-Based GeSn Lasers with Wavelength Coverage of 2–3 μm and Operating Temperatures up to 180 K

Margetis¹,

et al. 2017

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A Si-based monolithic laser is highly desirable for full integration of Si-photonics. Lasing from direct bandgap group-IV GeSn alloy has opened a completely new venue from the traditional III-V 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 for using similar deposition chemistries.The highest lasing temperature was measured as 180 K with the active layer thickness as thin as 2 260 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.Si-based electronics industry has driven the digital revolution for an unprecedented success.As a result, there has been tremendous effort to broaden the reach of Si technology to build integrated photonics 1-3 . Although great success has been made on Si-based waveguides 4 , modulators 5 , and photodetectors 6,7 , 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 decade [8][9][10][11] . From the other side, a low solid solubility of Sn in Ge (<1%), low temperature growth techniques under nonequilibrium conditions have been successfully developed 20,21 , leading to the first experimental demonstration of direct bandgap GeSn alloy 22 and the optically pumped GeSn interband lasers [23][24][25] . The recent engagement of mainstream industrial chemical vapor deposition (CVD) reactors for the development of GeSn growth techniques has enabled those significant results, which implies that the growth method is manufacturable and can be transferred to the foundry/fab 3 . In this paper, we demonstrate the first set of optically pumped GeSn edge-emitting lasers that covers an unprecedented broad wavelength range from 2 to 3 μm with lower lasing threshold and higher operation temperature than all previous reports. This superior laser performance is attributed to the unique epitaxial growth approaches that were developed based on newly discovered growth dynamics. Contrary to the common belief that growing GeSn with high Sn fabrication of a thicker, defect-free GeSn top layer to maximize the mode overlap with it.Moreover, the material growth study revealed that there is still room to further improve the material quality by optimizing the growth conditions. References

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“…There is a noticeable trend of lower loss with increasing wavelength, which is indicative of sidewall scattering. If this is the dominant loss mechanism it has been previously shown that oxidation of waveguide sidewalls can reduce roughness, however with thermal Ge oxide, it would have to subsequently be stripped as it is not transparent in the MIR [9]. In terms of reducing the loss caused from the overlap with the Si substrate there are multiple approaches that can be taken.…”

Section: Figure 1 the Propagation Losses Measured From A 4 µM Wide Gmentioning

confidence: 99%

Ge-on-Si Mid-Infrared Waveguide Platform for Molecular Fingerprint Sensing

Gallacher

Millar

Griškevičiūtė

et al. 2020

2020 22nd International Conference on Transparent Optical Networks (ICTON)

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The mid-infrared spectral region is key to several large market applications such as security, healthcare and environmental monitoring. This is due to how chemical compounds can be detected from unique vibrational modes that absorb in the molecular 'fingerprint' region (6.7-20 µm wavelength). There is significant interest in realizing cheaper and smaller spectrometers based on waveguide integrated photonics. Here we demonstrate Geon-Si waveguides operating up to 11 µm wavelength with low propagation loss (~ 1 dB/cm). The performance of the waveguides is then demonstrated by measuring thin films that are used to calibrate the modal overlap for molecular sensing. Lastly, an ultra-broadband Ge-on-Si waveguide polarization rotator is presented. The fabricated polarization rotator devices demonstrate a polarization extinction ratio of ≥ 15 dB over a 2 µm bandwidth (9-11 µm wavelength) with an average insertion loss < 1 dB.

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Disentangling nonradiative recombination processes in Ge micro-crystals on Si substrates

Cited by 18 publications

References 34 publications

Spin-coherent dynamics and carrier lifetime in strained Ge1−xSnx semiconductors on silicon

Spin-coherent dynamics and carrier lifetime in strained Ge1−xSnx semiconductors on silicon

Si-Based GeSn Lasers with Wavelength Coverage of 2–3 μm and Operating Temperatures up to 180 K

Ge-on-Si Mid-Infrared Waveguide Platform for Molecular Fingerprint Sensing

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