Monolithic infrared silicon photonics: The rise of (Si)GeSn semiconductors

Moutanabbir, Oussama; Assali, Simone; Gong, Xiao; O’Reilly, Eoin P.; Broderick, Christopher A.; Marzban, Bahareh; Witzens, Jeremy; Du, Wei; Yu, Shui-Qing; Chelnokov, A.; Buca, D.; Nam, Donguk

doi:10.1063/5.0043511

Cited by 125 publications

(76 citation statements)

References 63 publications

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“…As an additional path towards jointly improving maximum lasing temperature and threshold, which are driven by the directness and the quality of the material, respectively, strain engineering in suspended microdisk lasers allows increasing the material directness at moderate Sn contents. This is why we are currently investigating concepts for electrically pumped GeSn microdisk lasers [40].…”

Section: Discussionmentioning

confidence: 99%

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Modeling of a SiGeSn quantum well laser

et al. 2021

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We present comprehensive modeling of a SiGeSn multi-quantum well laser that has been previously experimentally shown to feature an order of magnitude reduction in the optical pump threshold compared to bulk lasers. We combine experimental material data obtained over the last few years with k • p theory to adapt transport, optical gain, and optical loss models to this material system (drift-diffusion, thermionic emission, gain calculations, free carrier absorption, and intervalence band absorption). Good consistency is obtained with experimental data, and the main mechanisms limiting the laser performance are discussed. In particular, modeling results indicate a low non-radiative lifetime, in the 100 ps range for the investigated material stack, and lower than expected Γ-L energy separation and/or carrier confinement to play a dominant role in the device properties. Moreover, they further indicate that this laser emits in transverse magnetic polarization at higher temperatures due to lower intervalence band absorption losses. To the best of our knowledge, this is the first comprehensive modeling of experimentally realized SiGeSn lasers, taking the wealth of experimental material data accumulated over the past years into account. The methods described in this paper pave the way to predictive modeling of new (Si)GeSn laser device concepts.

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Section: Discussionmentioning

confidence: 99%

“…We are currently working on an electrically pumped suspended GeSn microdisk laser concept, a description of which can be found in Ref. [40].…”

Section: Device Descriptionmentioning

confidence: 99%

Modeling of a SiGeSn quantum well laser

et al. 2021

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“…[2] Germanium (Ge) has been extensively explored for such a laser owing to its CMOS compatibility and near-direct bandgap configuration. [3,4] Among various approaches to achieve the bandgap directness, strain engineering [5][6][7][8][9][10][11][12][13] and tin (Sn) alloying [14][15][16][17] have been considered as the two most promising paradigms.…”

Section: Complementarymentioning

confidence: 99%

“…[17] For instance, it has been suggested that a large content of Sn increases the nonradiative recombination rate, thus leading to the reduction of internal quantum efficiency which influences the lasing threshold significantly. [17] In addition, the Sn alloying is typically accompanied by the compressive strain in the GeSn layer due to the large lattice mismatch between GeSn and Ge buffer layers. [15] Such compressive strain reduces the directness of GeSn, [28,29] thereby hindering the lasing performance.…”

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confidence: 99%

Enhanced GeSn Microdisk Lasers Directly Released on Si

Kim

Assali

Burt

et al. 2021

Advanced Optical Materials

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complementarymetal-oxide-semiconductor (CMOS) processing limits the practical realization of these long-sought-after PICs. [2] Germanium (Ge) has been extensively explored for such a laser owing to its CMOS compatibility and near-direct bandgap configuration. [3,4] Among various approaches to achieve the bandgap directness, strain engineering [5][6][7][8][9][10][11][12][13] and tin (Sn) alloying [14][15][16][17] have been considered as the two most promising paradigms.While lasing action has been observed in strain-engineered Ge at low operating temperatures (<100 K), [18][19][20] the Sn alloying approach has made significant, steady progress toward achieving lasing at practically high temperature over the past few years. [21][22][23][24][25][26][27] Since the first lasing demonstration in GeSn at 90 K, [21] much effort has been focused on increasing the operating temperature. [21][22][23][24][25][26][27] A major route to this end has been to increase the Sn content to further increase the directness of GeSn alloys, [17] which enabled higher operating temperatures reaching 270 K. [27] However, the lasing thresholds at these elevated temperatures are very high (>800 kW cm −2 at 270 K). [27] The exact causes for such high threshold in direct bandgap GeSn lasers have been attributed to the material quality. [17] For instance, it has been suggested that a large content of Sn increases the nonradiative recombination rate, thus leading to the reduction of internal quantum efficiency which influences the lasing threshold significantly. [17] In addition, the Sn alloying is typically accompanied by the compressive strain in the GeSn layer due to the large lattice mismatch between GeSn and Ge buffer layers. [15] Such compressive strain reduces the directness of GeSn, [28,29] thereby hindering the lasing performance. [30] Additionally, the increase in Sn content requires a decrease in growth temperature, which is typically associated with a higher concentration of point defects (vacancies and vacancies complexes) that can also impact the laser performance due to carrier trapping. [31,32] Another route to improve the lasing performance is to simultaneously employ both strain engineering and Sn alloying. [28,33] Recently, a few research groups have made significant progress along this direction by relaxing the compressive strain [22,34] and also by inducing mechanical tensile strain in GeSn. [35,36] Despite the improved directness of strain-engineered GeSn over as-grown compressively strained GeSn, the suspended device configuration, which has thus far been necessary for GeSn alloys are promising candidates for complementary metal-oxidesemiconductor-compatible, tunable lasers. Relaxation of residual compressive strain in epitaxial GeSn has recently shown promise in improving the lasing performance. However, the suspended device configuration that is thus far introduced to relax the strain is destined to limit heat dissipation, thus hindering the device performance. Herein is demonstrated that strain-free GeSn microdisk laser ...

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“…Limited by lattice matching for hetero-epitaxy, so far most of the α-Sn thin films have been grown on InSb instead of Si because the latter has a large lattice mismatch of ∼20%. Ge-rich GeSn alloys on Si have been extensively explored in optoelectronics community [11][12][13][14] , but high Sn composition SnGe alloys have been rarely studied experimentally since they are well beyond the solubility limit 2 . Furthermore, the thermal stability is also limited by the phase transition to β-Sn at elevated temperatures.…”

Section: Introductionmentioning

confidence: 99%

Reversed Phase Transformation of β→α-Sn at Elevated Temperatures towards Quantum Material Integration on Silicon

Covian

Liu

Gardener

et al. 2021

Preprint

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α-Sn and SnGe alloys have recently attracted much attention as a new family of topological quantum materials. However, bulk α-Sn is thermodynamically stable only at <13°C. Moreover, scalable integration of α-Sn quantum materials/devices on Si has been hindered by a large lattice mismatch. To address these challenges, we demonstrate compressively strained α-Sn doped with 2-4 at.% Ge on a native oxide layer on Si, grown at 300-500°C through a reversed β-to-α-Sn phase transformation without relying on epitaxy. The size of α-Sn microdots reaches up to 200 nm, ~10x larger than the upper size limit for α-Sn formation reported before. Furthermore, the compressive strain makes it one of the few candidates for 3D topological Dirac semimetals with interesting applications in spintronics. We find that Ge-rich GeSn nanoclusters in the as-deposited materials seeded the reversed β-to-α-Sn transition at elevated temperatures. This process can be further optimized for SnGe quantum material and device integration on Si.

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Monolithic infrared silicon photonics: The rise of (Si)GeSn semiconductors

Cited by 125 publications

References 63 publications

Modeling of a SiGeSn quantum well laser

Modeling of a SiGeSn quantum well laser

Enhanced GeSn Microdisk Lasers Directly Released on Si

Reversed Phase Transformation of β→α-Sn at Elevated Temperatures towards Quantum Material Integration on Silicon

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