Raman scattering in Ge1−ySny alloys

D'Costa, V. R.; Tolle, John; Roucka, Radek; Poweleit, C. D.; Kouvetakis, John; Menéndez, José

doi:10.1016/j.ssc.2007.08.020

Cited by 117 publications

(110 citation statements)

References 26 publications

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“…The typical peak position of the Ge-Ge mode at 301 cm À1 shifts to 299.5 cm À1 after PLIE, indicating compressive strain buildup in the layer. 19 Moreover, a vibrational mode around 263 cm À1 , reported for excitation closer to the resonance frequency of the E 1 /E 1 þ D 1 optical transitions, 20 is clearly observed for the laser treated structure, confirming substitutional Sn from Ge-Sn bonds. The peak around 186 cm À1 is assigned to the Sn-Sn vibration mode.…”

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confidence: 69%

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Laser synthesis of germanium tin alloys on virtual germanium

et al. 2012

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confidence: 69%

“…18 The vibrational modes of fully strained and relaxed GeSn alloys 19,20 show a decreasing GeGe phonon frequency and an increasing peak asymmetry with increasing Sn concentration. Figure 5 shows the Raman spectra of the as-deposited (black dotted line) and the laser treated (red continuous line) Sn/v-Ge structures.…”

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confidence: 99%

Laser synthesis of germanium tin alloys on virtual germanium

et al. 2012

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“…Subsequently, due to this incorporation of Sn, the GeSn lattice is strained normal to the surface as shown by both the ð400Þx=2h XRD scans and the 2 24 XRD/RSM maps. Such substitutional Sn content should be reflected as a Raman shift of the LO Ge-Ge peak, according to the following formula: 40 Dx ¼ av þ be jj . The coefficients a and b are for the concentration and the strain, respectively, whereas v; e jj are the Sn concentration and the strain parallel to the surface, respectively.…”

Section: Discussionmentioning

confidence: 99%

Synthesis of Ge1−xSnx alloys by ion implantation and pulsed laser melting: Towards a group IV direct bandgap material

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Pastor

Gandhi

et al. 2016

Journal of Applied Physics

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The germanium-tin (Ge1−xSnx) material system is expected to be a direct bandgap group IV semiconductor at a Sn content of 6.5−11 at. %. Such Sn concentrations can be realized by non-equilibrium deposition techniques such as molecular beam epitaxy or chemical vapour deposition. In this report, the combination of ion implantation and pulsed laser melting is demonstrated to be an alternative promising method to produce a highly Sn concentrated alloy with a good crystal quality. The structural properties of the alloys such as soluble Sn concentration, strain distribution, and crystal quality have been characterized by Rutherford backscattering spectrometry, Raman spectroscopy, x ray diffraction, and transmission electron microscopy. It is shown that it is possible to produce a high quality alloy with up to 6.2 at. %Sn. The optical properties and electronic band structure have been studied by spectroscopic ellipsometry. The introduction of substitutional Sn into Ge is shown to either induce a splitting between light and heavy hole subbands or lower the conduction band at the Γ valley. Limitations and possible solutions to introducing higher Sn content into Ge that is sufficient for a direct bandgap transition are also discussed.

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“…Raman scattering measurements were carried out on GeSn alloys, together with a Ge (001) substrate as a reference. The peaks of the Ge-Ge LO mode and Ge-Sn mode are observed, 18,23,29 and their positions and widths are extracted through multi-peak curve fittings based on a combination of Gaussian and Lorentzian function. Clear shifts can be observed for both peaks at different Sn concentrations.…”

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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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Raman scattering in Ge1−ySny alloys

Cited by 117 publications

References 26 publications

Laser synthesis of germanium tin alloys on virtual germanium

Laser synthesis of germanium tin alloys on virtual germanium

Synthesis of Ge1−xSnx alloys by ion implantation and pulsed laser melting: Towards a group IV direct bandgap material

Structural properties of GeSn thin films grown by molecular beam epitaxy

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