Epitaxial growth of strained and unstrained GeSn alloys up to 25% Sn

Oehme, Michael; Kostecki, Konrad; Schmid, M.; Oliveira, Filipe; Kasper, E.; Schulze, Jörg

doi:10.1016/j.tsf.2013.10.064

Cited by 112 publications

(89 citation statements)

References 18 publications

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“…The most efficient way, in our opinion, to fabricate high quality, partially strain relaxed epilayers is to grow several hundred nanometer thick GeSn layers on Ge virtual substrates (Ge-VS). Significant progress has been made in recent years in epitaxy of these alloys by Chemical Vapor Deposition (CVD) [11][12][13] and Molecular Beam Epitaxy 14,15 . However, the low growth temperatures required for Sn incorporation still lead to an epitaxial breakdown in thick layers due to a strong increase of surface roughness for Sn concentrations > 10 at.% 14 .…”

Section: Introductionmentioning

confidence: 99%

Direct Bandgap Group IV Epitaxy on Si for Laser Applications

et al. 2015

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The recent observation of a fundamental direct bandgap for GeSn group IV alloys and the demonstration of low temperature lasing provide new perspectives to the fabrication of Si photonic circuits. This work addresses the progress in GeSn alloy epitaxy aiming at room temperature GeSn lasing. Chemical vapor deposition of direct bandgap GeSn alloys with a high -to L-valley energy separation and large thicknesses for efficient optical mode confinement is presented and discussed. Up to 1 µm thick GeSn layers with Sn contents up to 14 at.% were grown on thick relaxed Ge buffers, using Ge 2 H 6 and SnCl 4 precursors. Strong strain relaxation (up to 81 %) at 12.5 at.% Sn concentration, translating into an increased separation between -and L-valleys of about 60 meV, have been obtained without crystalline structure degradation, as revealed by Rutherford backscattering/ion channeling spectroscopy and Transmission Electron Microscopy. Room temperature transmission/reflection and photoluminescence measurements were performed to probe the optical properties of these alloys. The emission/absorption limit of GeSn alloys can be extended up to 3.5 µm (0.35 eV), making those alloys ideal candidates for optoelectronics in the mid-infrared region. Theoretical net gain calculations indicate that large room temperature laser gains should be reachable even without additional doping.

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Section: Introductionmentioning

confidence: 99%

Direct Bandgap Group IV Epitaxy on Si for Laser Applications

et al. 2015

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“…The non-equilibrium processes during MBE are effective to avoid Sn segregation, achieved by low temperature growth, strain engineering, etc. The Sn concentration in GeSn has reached the direct-indirect transition point by several groups, [17][18][19][20][21][22] and some are even much higher, for example 25% 23 and 27%. 24 However, the low growth temperature is a major limitation to obtain device-grade quality materials.…”

Section: Introductionmentioning

confidence: 99%

Structural properties of GeSn thin films grown by molecular beam epitaxy

et al. 2017

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GeSn thin films on Ge (001) with various Sn concentrations from 3.36 to 7.62% were grown by molecular beam epitaxy and characterized. The structural properties were analyzed by reciprocal space mapping in the symmetric (004) and asymmetric (224) planes by high resolution X-ray diffraction (XRD). The lateral correlation length (LCL) and the mosaic spread (MS) were extracted for the epi-layer peaks in the asymmetric (224) diffraction. With the increase of Sn concentration, the LCL reduces while the MS increases, indicating degrading crystalline quality. Dislocations were observed in the sample with 7.62% Sn concentration by transmission electron microscope, consistent with the strain relaxation found in XRD mapping. Besides, the surface morphologies were investigated.

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“…concentration have been grown by low temperature molecular beam epitaxy (MBE), 12 chemical vapor deposition [13][14][15][16] or solid phase epitaxy. 17 Moreover, some ultra-high Sn concentration GeSn alloy has been grown by MBE at a growth temperature less than 200 • C, for example 25% 18 and 27%. 19 The non-equilibrium processes during MBE are effective to avoid Sn segregation.…”

Section: Introductionmentioning

confidence: 99%

“…20 However, low temperature MBE growth of GeSn alloy will introduce many defects, 21 which are detrimental to light emission from such a material. 18,22 Therefore, to obtain high quality and direct bandgap GeSn alloy, the dilemma between the Sn segregation at a high growth temperature and the high defect density introduced at a low growth temperature must be overcome. 23 Thermal annealing leads to decrease in defect density and improves optical quality of the GeSn alloy.…”

Section: Introductionmentioning

confidence: 99%

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Effect of thermal annealing on structural properties of GeSn thin films grown by molecular beam epitaxy

Zhang

Song

et al. 2017

AIP Advances

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GeSn alloy with 7.68% Sn concentration grown by molecular beam epitaxy has been rapidly annealed at different temperatures from 300°C to 800°C. Surface morphology and roughness annealed below or equal to 500°C for 1 min have no obvious changes, while the strain relaxation rate increasing. When the annealing temperature is above or equal to 600°C, significant changes occur in surface morphology and roughness, and Sn precipitation is observed at 700°C. The structural properties are analyzed by reciprocal space mapping in the symmetric (004) and asymmetric (224) planes by high resolution X-ray diffraction. The lateral correlation length and the mosaic spread are extracted for the epi-layer peaks in the asymmetric (224) diffraction. The most suitable annealing temperature to improve both the GeSn lattice quality and relaxation rate is about 500°C.

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Epitaxial growth of strained and unstrained GeSn alloys up to 25% Sn

Cited by 112 publications

References 18 publications

Direct Bandgap Group IV Epitaxy on Si for Laser Applications

Direct Bandgap Group IV Epitaxy on Si for Laser Applications

Structural properties of GeSn thin films grown by molecular beam epitaxy

Effect of thermal annealing on structural properties of GeSn thin films grown by molecular beam epitaxy

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