Structural and optical studies of strain relaxation in Ge1−xSnx layers grown on Ge/Si(001) by molecular beam epitaxy

Nikolenko, A. S.; Strelchuk, V. V.; Safriuk, N. V.; Kryvyi, Serhii; Kladko, V. P.; Oberemok, O.; Borkovska, L.; Sadofyev, Yu. G.

doi:10.1016/j.tsf.2015.10.065

“…High carrier mobility can contribute to improving the speed of the field effect transistors. The Optical and electronic properties of semiconductor alloys are related to the structure of the films, including the degree of strain, surface roughness, dislocation density, etc [5][6][7][8]. Effects of the structure on optoelectronic properties for GeSn films are still elusive.…”

Section: Introductionmentioning

confidence: 99%

Optoelectronic properties for the compressively strained Ge_1−xSn_x films grown on Ge(004)

Tao

¹

,

Tang

²

,

Wang

³

et al. 2020

Mater. Res. Express

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Compressively strained Ge1-xSnx films (x = 0.04, 0.08, 0.14) have been grown on Ge(004) substrates by Molecular Beam Epitaxy. The wavelength dependence of the refractive index is deduced as n ( x , λ ) = n Ge ( λ ) + ( ‐ 2 + 3.5 λ ) x + 5 ( 1 ‐ λ ) x 2 in the near-infrared range (NIR) (800–1700 nm) for Ge1-xSnx alloy films. That is similar to Si1-xGex alloy films. The Hall measurement shows that the donor levels decrease due to dislocation at room temperature. Temperature dependence of the electron mobility for Ge1-xSnx films reveals that strain-induced defects lower the carrier mobility from 10 K to 310 K. The maximum carrier mobility reaches 2082 cm2/V·s at T = 122 K for Ge0.96Sn0.04/Ge film. These results indicate that Sn-doping has great influences on electronic properties for Ge1-xSnx alloys. Our investigations may be helpful for fabricating the high performance optoelectronic devices.

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“…The low solubility of Sn and Ge (>1%) [13], Sn surface segregation [14] and huge lattice mismatch between α-Sn and Germanium [15] make the growing of epitaxial Ge 1−x Sn x films difficult and introduce more challenges. However, non-equilibrium growth approaches have been developed for growing GeSn alloys; including molecular beam epitaxy (MBE) [16,17], chemical vapor deposition (CVD) [18,19,20], solid phase epitaxy (SPE) [21], pulsed laser deposition (PLD) [22], and magnetron sputtering [12,23,24]. Consequently, high-quality epitaxial Ge 1−x Sn x alloy film have been grown by these techniques.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Ge1−xSnx Alloy Thin Films by Rapid Thermal Annealing of Sputtered Ge/Sn/Ge Layers on Si Substrates

Mahmodi

¹

,

Hashim

²

,

Soga

³

et al. 2018

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In this work, nanocrystalline Ge1−xSnx alloy formation from a rapid thermal annealed Ge/Sn/Ge multilayer has been presented. The multilayer was magnetron sputtered onto the Silicon substrate. This was followed by annealing the layers by rapid thermal annealing, at temperatures of 300 °C, 350 °C, 400 °C, and 450 °C, for 10 s. Then, the effect of thermal annealing on the morphological, structural, and optical characteristics of the synthesized Ge1−xSnx alloys were investigated. The nanocrystalline Ge1−xSnx formation was revealed by high-resolution X-ray diffraction (HR-XRD) measurements, which showed the orientation of (111). Raman results showed that phonon intensities of the Ge-Ge vibrations were improved with an increase in the annealing temperature. The results evidently showed that raising the annealing temperature led to improvements in the crystalline quality of the layers. It was demonstrated that Ge-Sn solid-phase mixing had occurred at a low temperature of 400 °C, which led to the creation of a Ge1−xSnx alloy. In addition, spectral photo-responsivity of a fabricated Ge1−xSnx metal-semiconductor-metal (MSM) photodetector exhibited its extending wavelength into the near-infrared region (820 nm).

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“…Thus far, the preferred method for growing compressively strained samples has been solid source molecular beam epitaxy (MBE) on Ge wafers and on Ge-buffered Si substrates. The ultra-low temperatures afforded by this technique ensure the pseudomorphic growth of the epilayers on the underlying Ge platform, leading to latticecoherent films with thicknesses comparable to the critical values [23][24][25][26][27][28][29]. Such films have been used to study the fundamental optical properties of strained alloys [30,31], to investigate their relaxation behavior [23,[27][28][29], and to fabricate LEDs and photodetectors as a function of composition [32][33][34].…”

Section: Introductionmentioning

confidence: 99%

Molecular epitaxy of pseudomorphic Ge_1−ySn_y(y= 0.06–0.17) structures and devices on Si/Ge at ultra-low temperatures via reactions of Ge₄H₁₀and SnD₄

Wallace

¹

,

Senaratne

²

,

Xu

³

et al. 2017

Semicond. Sci. Technol.

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A low-pressure CVD technique was specifically developed to prepare a new class of pseudomorphic Ge 1−y Sn y layers, with an Sn content up to 17% on Ge-buffered Si(100) wafers. The growth is conducted via reactions of SnD 4 and the recently deployed Ge 4 H 10 custom precursor, whose large molecular weight and enhanced reactivity enables depositions at unprecedented ultra-low temperatures (150 °C-200 °C), and at pressures akin to those typically employed in solid/gas-source MBE. The thicknesses of the layers far exceed the critical limits predicted by thermodynamic considerations and are either comparable to, or larger than, those observed for MBE-grown samples. This is validated by modeling of the thickness versus the composition for the fully strained and partially relaxed alloys produced in this work relative to the MBE and CVD-grown analogs reported in the literature. Furthermore, the practical relevance of the technique was demonstrated by creating highly doped n-type alloys, which were then used as active layers to fabricate degenerate pn junctions. It was also found that the strained films gradually relax with increasing thickness, providing new types of strain-free material with enhanced optical quality relative to those produced by standard CVD methods, as evidenced by the photoluminescence studies. The strain relaxation mechanism appears to be similar to that observed in CVD-grown samples, with no sign of epitaxial breakdown or precipitous degradation of the bulk crystallinity or surface morphology, in spite of the low growth temperatures employed. Finally, we note that this method represents the first example of a chemically driven route that delivers materials with the desirable properties afforded by MBE, while offering the potential for those practical applications inherent to large-scale CVD.

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Structural and optical studies of strain relaxation in Ge1−xSnx layers grown on Ge/Si(001) by molecular beam epitaxy

Cited by 5 publications

References 36 publications

Optoelectronic properties for the compressively strained Ge_1−xSn_x films grown on Ge(004)

Optoelectronic properties for the compressively strained Ge_1−xSn_x films grown on Ge(004)

Synthesis of Ge1−xSnx Alloy Thin Films by Rapid Thermal Annealing of Sputtered Ge/Sn/Ge Layers on Si Substrates

Molecular epitaxy of pseudomorphic Ge_1−ySn_y(y= 0.06–0.17) structures and devices on Si/Ge at ultra-low temperatures via reactions of Ge₄H₁₀and SnD₄

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Structural and optical studies of strain relaxation in Ge1−xSnx layers grown on Ge/Si(001) by molecular beam epitaxy

Cited by 5 publications

References 36 publications

Optoelectronic properties for the compressively strained Ge1−xSnx films grown on Ge(004)

Optoelectronic properties for the compressively strained Ge1−xSnx films grown on Ge(004)

Synthesis of Ge1−xSnx Alloy Thin Films by Rapid Thermal Annealing of Sputtered Ge/Sn/Ge Layers on Si Substrates

Molecular epitaxy of pseudomorphic Ge1−ySny(y= 0.06–0.17) structures and devices on Si/Ge at ultra-low temperatures via reactions of Ge4H10and SnD4

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Optoelectronic properties for the compressively strained Ge_1−xSn_x films grown on Ge(004)

Optoelectronic properties for the compressively strained Ge_1−xSn_x films grown on Ge(004)

Molecular epitaxy of pseudomorphic Ge_1−ySn_y(y= 0.06–0.17) structures and devices on Si/Ge at ultra-low temperatures via reactions of Ge₄H₁₀and SnD₄