Dielectric function and band structure of Sn1−xGex (x &amp;lt; 0.06) alloys on InSb

Carrasco, Rigo A.; Zollner, Stefan; Chastang, Stephanie A.; Duan, Jingliang; Grzybowski, Gordon; Claflin, B.; Kiefer, Arnold

doi:10.1063/1.5086742

Cited by 4 publications

(3 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Both predictions seem to disagree with recent measurements on samples with y > 0.94 (Ref. 19), but the discrepancy should be interpreted with caution because the E0 transition in α-Sn has a unique line shape that is not fully understood. 29 The difference between the LC&L prediction and the best fit in Fig.…”

contrasting

confidence: 75%

See 1 more Smart Citation

Mid-infrared (3–8 μm) Ge1−ySny alloys (0.15 < y < 0.30): Synthesis, structural, and optical properties

Wallace

Ringwala

et al. 2019

Applied Physics Letters

View full text Add to dashboard Cite

Ge1-ySny alloys with compositions in the 0.15 < y < 0.30 range have been grown directly on Si substrates using a chemical vapor deposition approach that allows for growth temperatures as high as 290 o C. The films show structural properties that are consistent with results from earlier materials with much lower Sn concentrations. These include the lattice parameter and the Ge-Ge Raman frequency, which are found to depend linearly on composition. The simplicity of the structures, directly grown on Si, makes it possible to carry out detailed optical studies. Sharp absorption edges are found, reaching 8 μm near y =0.3. The compositional dependence of edge energies shows a cubic deviation from the standard quadratic alloy expression. The cubic term may dramatically impact the ability of the alloys to cover the long-wavelength (8-12 μm) mid-IR atmospheric window. * chixu@asu.edu

show abstract

contrasting

confidence: 75%

“…The small grey circles over a grey background are from Ref. 17, the grey squares are from this work, and the grey triangles are from Ref 19…”

mentioning

confidence: 99%

Mid-infrared (3–8 μm) Ge1−ySny alloys (0.15 < y < 0.30): Synthesis, structural, and optical properties

Wallace

Ringwala

et al. 2019

Applied Physics Letters

View full text Add to dashboard Cite

show abstract

“…Optical transitions in Ge 1– x Si x alloys have been shown to evolve smoothly from Ge-like to Si-like, and a similar behavior has been observed in many III–V and II–VI pseudobinary alloy systems. For Ge 1– y Sn y , the compositional dependence of optical transitions has been studied in detail in the dilute alloy regimes near both ends of the compositional spectrum. − A question of considerable interest is the extent to which the compositional dependencies derived in these dilute regimes remain valid over the entire compositional range. Even more fundamentally, such compositional dependencies are associated with an implicit virtual crystal/coherent potential approximation description of the electronic structure, which might very well break down into nondilute alloys because of the very large size mismatch between Ge and Sn and the presence of Sn–Sn bonds.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Fundamental Studies of Si-Compatible (Si)GeSn and GeSn Mid-IR Systems with Ultrahigh Sn Contents

Ringwala

Wang

et al. 2019

Chem. Mater.

View full text Add to dashboard Cite

A unique class of crystalline Ge 1−y Sn y alloys with ultrahigh Sn concentrations reaching 33% as well as Si-doped analogues have been synthesized directly on large-area Si wafers by chemical vapor deposition (CVD). The band gaps of these materials are measured to be as low as 0.15 eV, which allows them to cover a significant portion of the coveted mid-IR optical range past 8 μm, making them a potential alternative to Hg 1−x Cd x Te for long-wavelength applications. The film synthesis, based on stoichiometric CVD reactions of polygermanes and stannanes, is carried out at temperatures between 240 and 290 °C, indicating that the alloys are stable at typical device-operating temperatures and at complementary metal oxide semiconductorcompatible conditions. The main difference between Ge 1−y Sn y (y ≈ 0.33) and the more diluted alloys (y < ∼0.2) featured in prior studies is the predicted presence of a significant fraction of Sn−Sn bonds, which could have a profound impact on the structural and electronic properties in view of the large size mismatch between Ge and Sn. However, X-ray measurements of the lattice parameter over the entire 0−33% Sn compositional range show a linear dependence of the cubic lattice parameter consistent with Vegard's law. Theoretical ab initio simulations assuming random alloys show a monotonic compositional dependence of the alloy energy of formation and confirm the experimental lattice parameter. The crystalline structure and the interface defects that accommodate the large lattice mismatch with the substrate are elucidated using transmission electron microscopy studies. Optical studies indicate that the fundamental direct band gap and other critical point features in the electronic structure also display a smooth compositional dependence, which should facilitate device engineering based on these materials.

show abstract

Band structure critical point energy in germanium–tin alloys with high tin contents

Imbrenda

Carrasco

Hickey

et al. 2021

Applied Physics Letters

View full text Add to dashboard Cite

The dielectric functions of germanium–tin alloy thin-films, deposited by molecular beam epitaxy on bulk Ge substrates, with relatively high Sn contents from 15 to 27 at. %, were measured by variable angle spectroscopic ellipsometry over the wavelength range from 0.190 to 6 μm, using a combination of ultraviolet-visible and infrared ellipsometers. The band structure critical point energies, specifically the E1 and E1 + Δ1 optical transitions, were extracted from the measurements by a method of parametric oscillator modeling and second derivative analysis. With increasing Sn content, the transitions shifted to lower energies, and for alloys with less than 20% Sn, the numerical values agreed reasonably with predictions based on deformation potential theory that accounted for film strain. For the higher Sn alloys, the critical point energies from measurements agreed less well with deformation potential theory. These results provide information on the band structure of GeSn alloys with high Sn contents, which are increasingly important for long-wave infrared devices and applications.

show abstract

Dielectric function and band structure of Sn1−xGex (x < 0.06) alloys on InSb

Cited by 4 publications

References 20 publications

Mid-infrared (3–8 μm) Ge1−ySny alloys (0.15 < y < 0.30): Synthesis, structural, and optical properties

Mid-infrared (3–8 μm) Ge1−ySny alloys (0.15 < y < 0.30): Synthesis, structural, and optical properties

Synthesis and Fundamental Studies of Si-Compatible (Si)GeSn and GeSn Mid-IR Systems with Ultrahigh Sn Contents

Band structure critical point energy in germanium–tin alloys with high tin contents

Contact Info

Product

Resources

About

Dielectric function and band structure of Sn1−xGex (x &lt; 0.06) alloys on InSb

Cited by 4 publications

References 20 publications

Mid-infrared (3–8 μm) Ge1−ySny alloys (0.15 &lt; y &lt; 0.30): Synthesis, structural, and optical properties

Mid-infrared (3–8 μm) Ge1−ySny alloys (0.15 &lt; y &lt; 0.30): Synthesis, structural, and optical properties

Synthesis and Fundamental Studies of Si-Compatible (Si)GeSn and GeSn Mid-IR Systems with Ultrahigh Sn Contents

Band structure critical point energy in germanium–tin alloys with high tin contents

Contact Info

Product

Resources

About

Dielectric function and band structure of Sn1−xGex (x < 0.06) alloys on InSb

Mid-infrared (3–8 μm) Ge1−ySny alloys (0.15 < y < 0.30): Synthesis, structural, and optical properties

Mid-infrared (3–8 μm) Ge1−ySny alloys (0.15 < y < 0.30): Synthesis, structural, and optical properties