Short-wave infrared LEDs from GeSn/SiGeSn multiple quantum wells

Stange, Daniela; Driesch, Nils von den; Rainko, Denis; Roesgaard, Søren; Povstugar, Ivan; Hartmann, Jean‐Michel; Stoïca, T.; Ikonić, Z.; Mantl, S.; Grützmacher, Detlev; Buca, D.

doi:10.1364/optica.4.000185

Cited by 106 publications

(77 citation statements)

References 23 publications

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“…Heterostructures like presented in Ref. 38 , combined with tensile strain, would strongly improve the carrier confinement at higher temperatures and, consequently, further decrease the threshold pump power density. QWs heterostructures design allows the separation of the active region from interface defects without using a layer transfer technology, which is desirable for low-cost, high yield fabrication.…”

Section: /12mentioning

confidence: 97%

Ultra-low-threshold continuous-wave and pulsed lasing in tensile-strained GeSn alloys

et al. 2020

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GeSn alloys are the most promising semiconductors for light emitters entirely based on group IV elements. Alloys containing more than 8 at. % Sn have fundamental direct band-gaps, similar to conventional III-V semiconductors and thus can be employed for light emitting devices. Here, we report on GeSn microdisk lasers encapsulated with a SiN x stressor layer to produce tensile strain. A 300 nm GeSn layer with 5.4 at. % Sn, which is an indirect band-gap semiconductor as-grown with a compressive strain of −0.32 %, is transformed via tensile strain engineering into a truly direct band-gap semiconductor. In this approach the low Sn concentration enables improved defect engineering and the tensile strain delivers a low density of states at the valence band edge, which is the light hole band. Continuous wave (cw) as well as pulsed lasing are observed at very low optical pump powers. Lasers with emission wavelength of 2.5 µm have thresholds as low as 0.8 kW cm −2 for ns-pulsed excitation, and 1.1 kW cm −2 under cw excitation. These thresholds are more than two orders of magnitude lower than those previously reported for bulk GeSn lasers, approaching these values obtained for III-V lasers on Si. The present results demonstrate the feasabiliy and are the guideline for monolithically integrated Si-based laser sources on Si photonics platform. arXiv:2001.04927v1 [physics.app-ph] 14 Jan 2020 at an Sn concentration of 8 at. % 3 . The lattice mismatch between Sn-containing alloys and the Ge buffer layer, the typical virtual substrate for their epitaxial growth, generates compressive strain in the grown layer, which counteracts the effect of Sn incorporation, decreasing the directness ∆E L−Γ = E L − E Γ . On the contrary, applying tensile strain will increase the directness. Finding a proper balance between a moderate Sn content to minimize crystal defects and to maintain thermal stability of the GeSn alloy on one hand and making use of tensile strain on the other hand are the keys to bring lasing threshold and operation temperature close to application's requirements. The mainstream research to increase ∆E L−Γ focuses on high Sn content alloys 5, 12 , obtained by epitaxy of thick strain-relaxed GeSn layers. A large directnesss is obtained, leading to higher temperature operation, although at the expense of steadily increasing laser threshold 13 . We have recently theoretically proposed an alternative approach, which is based on two key ingredients: employing moderate Sn content GeSn alloys, and inducing tensile strain in them 14 . This study indicated that, if a given directness is reached via tensile strain rather than by increasing Sn content, the material can provide a higher net gain. The underlying physics originates in the valence band splitting and lifting up of the light hole, LH, band above the heavy hole, HH, band. Its lower density of states (DOS) reduces the carrier density required for transparency, hence reduces the lasing threshold, as will be shown below. GeSn alloys with a moderate Sn content offer a couple of ...

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Section: /12mentioning

confidence: 97%

Ultra-low-threshold continuous-wave and pulsed lasing in tensile-strained GeSn alloys

et al. 2020

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“…[1][2][3][4][5][6][7][8][9] The successful demonstration of direct bandgap GeSn light emitting diodes (LEDs), and optically-pumped GeSn lasers, [10][11][12][13][14] indicates the great potential of GeSn for Si-based light sources. GeSn LEDs with double heterostructures (DHS) 11,[15][16][17][18][19][20][21][22] and quantum wells (QWs) [23][24][25][26][27][28][29][30][31] have been reported. It is generally acknowledged that the QW structures could be applied to the LEDs and lasers to improve their device performance.…”

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confidence: 99%

“…23,24,32,33 By engineering the Si and Sn composition, using SiGeSn as barrier, the carrier confinement in the QW was improved compared to those using Ge as barrier. Moreover, the band structure analysis and characterization results indicated that the direct bandgap well could be achieved by using high-Sn GeSn material, 23,24 which is desired for the improvement of the light emission efficiency. However, an in-depth study including detailed band structure calculation and optical transition has not been performed on a direct bandgap GeSn QW so far.…”

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confidence: 99%

Direct bandgap type-I GeSn/GeSn quantum well on a GeSn- and Ge- buffered Si substrate

et al. 2018

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This paper reports the comprehensive characterization of a Ge0.92Sn0.08/Ge0.86Sn0.14/Ge0.92Sn0.08 single quantum well. By using a strain relaxed Ge0.92Sn0.08 buffer, the direct bandgap Ge0.86Sn0.14 QW was achieved, which is unattainable by using only a Ge buffer. Band structure calculations and optical transition analysis revealed that the quantum well features type-I band alignment. The photoluminescence spectra showed dramatically increased quantum well peak intensity at lower temperature, confirming that the Ge0.86Sn0.14 quantum well is a direct bandgap material.

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“…Considering that band gap can be adjusted by adding Sn content, GeSn material can be applied for light emitting devices, including laser and LED. It has been reported that the related work is underway in laser [38][39][40] and light emission [41][42][43] . However, most of work is just focused on optical pumping at low temperature and the luminous efficiency is low.…”

Section: Outlook and Summarymentioning

confidence: 99%

Germanium-tin alloys: applications for optoelectronics in mid-infrared spectra

Fang

Liu

Zhang

et al. 2018

Opto-Electronic Advances

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We summarize our work of the optoelectronic devices based on Germanium-tin (GeSn) alloys assisted with the Si 3 N 4 liner stressor in mid-infrared (MIR) domains. The device characteristics are thoroughly analyzed by the strain distribution, band structure, and absorption characteristics. Numerical and analytical methods show that with optimal structural parameters, the device performance can be further improved and the wavelength application range can be extended to 2~5 μm in the mid-infrared spectra. It is demonstrated that this proposed strategy provides an effective technique for the strained-GeSn devices in future optical designs, which will be competitive for the optoelectronics applications in mid-infrared wavelength.

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Short-wave infrared LEDs from GeSn/SiGeSn multiple quantum wells

Cited by 106 publications

References 23 publications

Ultra-low-threshold continuous-wave and pulsed lasing in tensile-strained GeSn alloys

Ultra-low-threshold continuous-wave and pulsed lasing in tensile-strained GeSn alloys

Direct bandgap type-I GeSn/GeSn quantum well on a GeSn- and Ge- buffered Si substrate

Germanium-tin alloys: applications for optoelectronics in mid-infrared spectra

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