Ge-on-Si laser operating at room temperature

Liu, Jifeng; Sun, Xiaochen; Camacho-Aguilera, Rodolfo; Kimerling, Lionel C.; Michel, Jürgen

doi:10.1364/ol.35.000679

Cited by 872 publications

(624 citation statements)

References 19 publications

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“…Moreover, the method presented here can be applied to any pseudomorphically grown tensilestrained heterostructure material system as it depends purely on geometrical factors. As an example, apart from the application to silicon NWs, this approach could very well be applied to micrometre thick strained Ge layers for photonic applications 26 .…”

Section: Discussionmentioning

confidence: 99%

Top-down fabricated silicon nanowires under tensile elastic strain up to 4.5%

et al. 2012

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strained si nanowires are among the most promising transistor structures for implementation in very large-scale integration due to of their superior electrostatic control and enhanced transport properties. Realizing even higher strain levels within such nanowires are thus one of the current challenges in microelectronics. Here we achieve 4.5% of elastic strain (7.6 GPa uniaxial tensile stress) in 30 nm wide si nanowires, which considerably exceeds the limit that can be obtained using siGe-based virtual substrates. our approach is based on strain accumulation mechanisms in suspended dumbbell-shaped bridges patterned on strained si-on-insulator, and is compatible with complementary metal oxide semiconductor fabrication. Potentially, this method can be applied to any tensile prestrained layer, provided the layer can be released from the substrate, enabling the fabrication of a variety of strained semiconductors with unique properties for applications in nanoelectronics, photonics and photovoltaics. This method also opens up opportunities for research on strained materials.

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Section: Discussionmentioning

confidence: 99%

Top-down fabricated silicon nanowires under tensile elastic strain up to 4.5%

et al. 2012

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“…To compensate for this energy difference and thus form a laser gain medium, heavy n-type doping of slightly tensile strained Ge has been proposed 19 . Later, laser action has been reported for optically 20 and electrically pumped Ge 21 doped to approx. 1 and 4×10 19 cm -3 , respectively.…”

Section: Direct Bandgap Group IV Materials May Thus Represent a Pathwmentioning

confidence: 99%

Lasing in direct-bandgap GeSn alloy grown on Si

et al. 2015

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Direct bandgap group IV materials may thus represent a pathway towards the monolithic integration of Si-photonic circuitry and CMOS technology.Although a group IV direct bandgap material has not been demonstrated yet, silicon photonics using CMOS-compatible processes has made great progress through the development of Si-based waveguides 12 , photodetectors 13 and modulators 14 . The thus emerging technology is rapidly expanding the landscape of photonics applications towards tele-and data communication as well as sensing from the infrared to the mid infrared wavelength range 15-17 . Today's light sources of such systems are lasers made from direct bandgap group III-V materials operated off-or on-chip which requires fibre coupling or heterogeneous integration, for example by wafer bonding 3 , contact printing 4,5 or direct growth 6,7 , respectively. Hence, a laser source made of a direct bandgap group IV material would further boost lab-on-a-chip and trace gas sensing 15 as well as optical interconnects 18 by enabling monolithic integration. In this context, Ge plays a prominent role since the conduction band minimum at the -point of the Brillouin-zone (referred to as -valley) is 3 located only approx. 140 meV above the fourfold degenerate indirect L-valley. To compensate for this energy difference and thus form a laser gain medium, heavy n-type doping of slightly tensile strained Ge has been proposed 19 . Later, laser action has been reported for optically 20 and electrically pumped Ge 21 doped to approx. 1 and 4×10 19 cm -3 , respectively. However, pump-probe measurements of similarly doped and strained material did not show evidence for net gain 22 , and in spite of numerous attempts, researchers failed to substantiate above results up to today. Other investigated concepts concern the engineering of the Ge band structure towards a direct bandgap semiconductor using micromechanicallystressed Ge nanomembranes 9 or silicon nitride (Si 3 N 4 ) stressor layers 23 . Very recently, Süess et al. 10 presented a stressor-free technique which enables the introduction of more than 5.7 % 24 uniaxial tensile strain in Ge µ-bridges via selective wet under-etching of a pre-stressedlayer. An alternative technique in order to achieve direct bandgap material is to incorporate Sn atoms into a Ge lattice, which primarily reduces the gap at the -point. At a sufficiently high fraction of Sn, the energy of the -valley decreases below that of the L-valley. This indirect-to-direct transition for relaxed GeSn binaries has been predicted to occur at about 20 % Sn by Jenkins et al. 25 , but more recent calculations indicate much lower required Sn concentrations in the range of 6.5-11.0 % 26,27 . A major challenge for the realization of such GeSn alloys is the low (< 1 %) equilibrium solubility of Sn in Ge 28 and the large lattice mismatch of about 15 % between Ge and -Sn. For GeSn grown on Ge substrates, this mismatch induces biaxial compressive strain causing a shift of the  and L-valley crossover towards higher Sn concentrations ...

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“…5,6 This feature is crucial for the effective implementation of spintronic devices, 7 and quantum information processing. 2,5,8 Only very recently, however, the quasi-direct behavior of Ge has sparked interest in its photonic properties, 9,10 and stimulated the use of various optical schemes aiming at addressing its spin physics. [11][12][13][14] In Ge, the absolute minimum of the conduction band (CB) is at the L point of the Brillouin zone, but there exists a local minimum at the zone-center Γ.…”

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confidence: 99%

Spin and energy relaxation in germanium studied by spin-polarized direct-gap photoluminescence

et al. 2013

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Spin orientation of photoexcited carriers and their energy relaxation is investigated in bulk Ge by studying spin-polarized recombination across the direct band gap. The control over parameters such as doping and lattice temperature is shown to yield high polarization degree, namely larger than 40%, as well as a fine-tuning of the angular momentum of the emitted light with a complete reversal between right-and left-handed circular polarization. By combining the measurement of the optical polarization state of band-edge luminescence and Monte Carlo simulations of carrier dynamics, we show that these very rich and complex phenomena are the result of the electron thermalization and cooling in the multi-valley conduction band of Ge. The circular polarization of the direct-gap radiative recombination is indeed affected by energy relaxation of hot electrons via the X valleys and the Coulomb interaction with extrinsic carriers. Finally, thermal activation of unpolarized L valley electrons accounts for the luminescence depolarization in the high temperature regime.

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Ge-on-Si laser operating at room temperature

Cited by 872 publications

References 19 publications

Top-down fabricated silicon nanowires under tensile elastic strain up to 4.5%

Top-down fabricated silicon nanowires under tensile elastic strain up to 4.5%

Lasing in direct-bandgap GeSn alloy grown on Si

Spin and energy relaxation in germanium studied by spin-polarized direct-gap photoluminescence

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