Pseudomorphic GeSn/Ge(001) quantum wells: Examining indirect band gap bowing

Tonkikh, A. A.; Eisenschmidt, C.; Talalaev, V. G.; Zakharov, N. D.; Schilling, Joerg; Schmidt, G.; Werner, P.

doi:10.1063/1.4813913

Cited by 111 publications

(69 citation statements)

References 21 publications

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“…Further, it is expected that defectfree GeSn could be grown pseudomorphic (fully strained) onto relaxed Ge buffer layer or substrate with thickness below the critical thickness [15,16]. Recently, Alexander et al [17] studied the band gap character of compressively strained GeSn/Ge(001) quantum wells (QWs) grown by MBE and they demonstrated that these pseudomorphic layers could serve as active regions in light emitting devices in Ge-photonic circuits based on germanium-oninsulator substrates. GeSn p-i-n photodetectors with Sn contents up to 3.6% in active layer have been recently fabricated on Ge substrate with a cut-off detection wavelength reaching 1.95 µm [18].…”

Section: Introductionmentioning

confidence: 98%

Band engineering and absorption spectra in compressively strained Ge_0.92Sn_0.08/Ge (001) double quantum well for infrared photodetection

Yahyaoui

Sfina

Lazzari

et al. 2014

Phys. Status Solidi C

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We report a theoretical investigation of strained Ge1−xSnx/Ge (001)‐oriented quantum wells as a bulding block in active region of infrared photodetector. The electronic band parameters, gaps, discontinuities and effective masses for heterointerfaces between compressively strained Ge1−xSnx and relaxed Ge have beencomputed at room temperature. From this preliminary and mendatory work, we conclude that pseudomorphic Ge1−xSnx alloys become direct band gap semiconductors at a Sn‐fraction of 15.3%, e.g. a lattice mismatch as high as 2.3%. Due to achievable critical layer thickness and mainly solid solubility limit, a type‐I compressively strained Ge/Ge0.92Sn0.08/Ge (double) quantum well is studied by solving Schrödinger equation without and applied bias voltage. A strong absorption coefficient (> 1×104 cm−1) and a Stark shift of the direct transition between 2.01 μm and 2.25 μm at large external fields (40kV/cm) are attractive characteristics for the design of infrared photodetectors (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Introductionmentioning

confidence: 98%

Band engineering and absorption spectra in compressively strained Ge_0.92Sn_0.08/Ge (001) double quantum well for infrared photodetection

Yahyaoui

Sfina

Lazzari

et al. 2014

Phys. Status Solidi C

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“…That peak may be related to a defect, such as dislocation in the Ge buffer layer. 37,38 Further investigation is needed to understand the type of the defect and the source of the emission. In Fig.…”

Section: Photoluminescencementioning

confidence: 99%

Optical Characterization of Si-Based Ge1−x Sn x Alloys with Sn Compositions up to 12%

Al-Kabi

Ghetmiri

Margetis

et al. 2015

Journal of Elec Materi

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Optical properties of germanium tin (Ge 1Àx Sn x ) alloys have been comprehensively studied with Sn compositions from 0 (Ge) to 12%. Raman spectra of the GeSn samples with various Sn compositions were measured. The room temperature photoluminescence (PL) spectra show a gradual shift of emission peaks towards longer wavelength as Sn composition increases. Temperature dependent PL shows the PL intensity variation along with the temperature change, which reveals the indirectness or directness of the bandgap of the material. As temperature decreases, the PL intensity decreases with Sn composition less than 8%, indicating the indirect bandgap Ge 1Àx Sn x ; while the PL intensity increases with Sn composition higher than 10%, implying the direct bandgap Ge 1Àx Sn x . Moreover, the PL study of n-doped samples shows bandgap narrowing compared to the unintentionally (Boron) doped thin film with similar Sn compositions due to the doping.

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“…In fact, fully pseudomorphic Ge/Ge 1Ày Sn y interfaces have been demonstrated by several groups. [20][21][22][23][24][25] While these interfaces are defect-free, compressive strain is undesirable because it increases the direct gap energy and the direct-indirect separation, suppressing the two key benefits of Sn alloying. Moreover, Ge 1Ày Sn y films partially compressed or fully strained to Ge-buffer layers are of limited or no value as Ge stressors.…”

Section: Introductionmentioning

confidence: 99%

Ge1-ySny (y = 0.01-0.10) alloys on Ge-buffered Si: Synthesis, microstructure, and optical properties

Senaratne

Gallagher

Jiang

et al. 2014

Journal of Applied Physics

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Novel hydride chemistries are employed to deposit light-emitting Ge1-ySny alloys with y ≤ 0.1 by Ultra-High Vacuum Chemical Vapor Deposition (UHV-CVD) on Ge-buffered Si wafers. The properties of the resultant materials are systematically compared with similar alloys grown directly on Si wafers. The fundamental difference between the two systems is a fivefold (and higher) decrease in lattice mismatch between film and virtual substrate, allowing direct integration of bulk-like crystals with planar surfaces and relatively low dislocation densities. For y ≤ 0.06, the CVD precursors used were digermane Ge2H6 and deuterated stannane SnD4. For y ≥ 0.06, the Ge precursor was changed to trigermane Ge3H8, whose higher reactivity enabled the fabrication of supersaturated samples with the target film parameters. In all cases, the Ge wafers were produced using tetragermane Ge4H10 as the Ge source. The photoluminescence intensity from Ge1−ySny/Ge films is expected to increase relative to Ge1−ySny/Si due to the less defected interface with the virtual substrate. However, while Ge1−ySny/Si films are largely relaxed, a significant amount of compressive strain may be present in the Ge1−ySny/Ge case. This compressive strain can reduce the emission intensity by increasing the separation between the direct and indirect edges. In this context, it is shown here that the proposed CVD approach to Ge1−ySny/Ge makes it possible to approach film thicknesses of about 1 μm, for which the strain is mostly relaxed and the photoluminescence intensity increases by one order of magnitude relative to Ge1−ySny/Si films. The observed strain relaxation is shown to be consistent with predictions from strain-relaxation models first developed for the Si1−xGex/Si system. The defect structure and atomic distributions in the films are studied in detail using advanced electron-microscopy techniques, including aberration corrected STEM imaging and EELS mapping of the average diamond–cubic lattice.

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Pseudomorphic GeSn/Ge(001) quantum wells: Examining indirect band gap bowing

Cited by 111 publications

References 21 publications

Band engineering and absorption spectra in compressively strained Ge_0.92Sn_0.08/Ge (001) double quantum well for infrared photodetection

Band engineering and absorption spectra in compressively strained Ge_0.92Sn_0.08/Ge (001) double quantum well for infrared photodetection

Optical Characterization of Si-Based Ge1−x Sn x Alloys with Sn Compositions up to 12%

Ge1-ySny (y = 0.01-0.10) alloys on Ge-buffered Si: Synthesis, microstructure, and optical properties

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Pseudomorphic GeSn/Ge(001) quantum wells: Examining indirect band gap bowing

Cited by 111 publications

References 21 publications

Band engineering and absorption spectra in compressively strained Ge0.92Sn0.08/Ge (001) double quantum well for infrared photodetection

Band engineering and absorption spectra in compressively strained Ge0.92Sn0.08/Ge (001) double quantum well for infrared photodetection

Optical Characterization of Si-Based Ge1−x Sn x Alloys with Sn Compositions up to 12%

Ge1-ySny (y = 0.01-0.10) alloys on Ge-buffered Si: Synthesis, microstructure, and optical properties

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Product

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Band engineering and absorption spectra in compressively strained Ge_0.92Sn_0.08/Ge (001) double quantum well for infrared photodetection

Band engineering and absorption spectra in compressively strained Ge_0.92Sn_0.08/Ge (001) double quantum well for infrared photodetection