Metal-enhanced Ge1−xSnx alloy film growth on glass substrates using a biaxial CaF2 buffer layer

Dash, Jatis Kumar; Chen, L.; Lu, Toh‐Ming; Wang, G.-C.; Zhang, L. H.; Kisslinger, Kim

doi:10.1039/c4ce01228c

Cited by 8 publications

(13 citation statements)

References 33 publications

(46 reference statements)

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“…However, these flakes do not form a continuous film covering the entire mica substrate . In our group we have demonstrated that biaxial continuous Sn films can be grown on the biaxial CaF 2 buffer layer on an amorphous substrate deposited by oblique angle deposition . One can imagine the possibility of depositing SnS films using SnS powders at an oblique angle deposition on an amorphous substrate to induce a biaxial texture instead of through the sulfurization of predeposited Sn.…”

Section: Results and Discussionmentioning

confidence: 99%

Tuning the Phase and Optical Properties of Ultrathin SnS_x Films

et al. 2016

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Novel materials suitable for optoelectronics are of great interest due to limited and diminishing energy resources and the movement toward a green earth. We report a simple film growth method to tune the S composition, x from 1 to 2 in semiconductor ultrathin SnS x films on quartz substrates, that is, single phase SnS, single phase SnS2, and mixed phases of both SnS and SnS2 by varying the sulfurization temperature from 150 to 500 °C. Due to the ultrathin nature of the SnS x films, their structural and optical properties are characterized and cross-checked by multiple surface-sensitive techniques. The grazing incidence X-ray diffraction (GIXRD) shows that the single phase SnS forms at 150 °C, single phase SnS2 forms at 350 °C and higher, and mixed phases of SnS and SnS2 form at temperature between. GIXRD shows structures of SnS film and SnS2 film are orthorhombic and 2H hexagonal, respectively. To complement the GIXRD, the reflection high energy electron diffraction pattern analysis shows that both pure phases are polycrystalline on the surface. Raman spectra support existence of pure phase SnS, pure phase SnS2, and mixed phases of SnS and SnS2. X-ray photoelectron spectroscopy reveals that the near surface stoichiometry of both single phase SnS and single phase SnS2 are close to Sn/S ratios of 1:1 and 1:2, respectively. UV–vis spectroscopy shows the optical absorption coefficient of SnS film is higher than 105 cm–1 above the optical bandgap of 1.38 ± 0.02 eV, an ideal optical absorber. A two-terminal device made of SnS film grown on SiO2 substrates shows good photoresponse. The SnS2 has an optical bandgap of 2.21 ± 0.02 eV. A photoluminescence (PL) peak of SnS2 film is observed at ∼542 nm. Time-resolved PL of the single phase ultrathin SnS2 film indicates a carrier lifetime of 1.62 ns, longer than sub nanosecond lifetime from multilayer SnS2. Our comprehensive results show that ultrathin SnS and SnS2 films have the required properties for potential photodetectors and solar cell applications but consume much less material as compared with current thin film devices.

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Section: Results and Discussionmentioning

confidence: 99%

Tuning the Phase and Optical Properties of Ultrathin SnS_x Films

et al. 2016

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“…Therefore, it is commonly used to evaluate the chemical composition and lattice properties of, for instance, group-IV semiconductors such as strained Si, 4-6 strained Ge, 7-10 SiGe, [11][12][13][14] and GeSn layers. [15][16][17][18][19][20][21][22][23][24][25] The latter are particularly of growing interest because of their relevance to Si-compatible light emission and detection applications in the short-and mid-wavelength infrared, [26][27][28][29][30][31][32][33][34][35] which can lead to the integration of optoelectronic and photonic circuits on complementary metal-oxide-semiconductor (CMOS) platforms. [36][37][38] Previous reports on the vibrational modes of GeSn mainly focused on Ge-Ge longitudinal optical (LO) mode as the analyses relied on the use of 488 nm 15,16 or 532 nm 18-24 excitation lines.…”

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confidence: 99%

Decoupling the effects of composition and strain on the vibrational modes of GeSn semiconductors

Bouthillier¹,

Assali²,

Nicolas³

et al. 2020

Semicond. Sci. Technol.

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We report on the behavior of Ge-Ge, Ge-Sn, Sn-Sn like and disorder-activated vibrational modes in GeSn semiconductors investigated using Raman scattering spectroscopy. By using an excitation wavelength close to E1 gap, all modes are clearly resolved and their evolution as a function of strain and Sn content is established. In order to decouple the individual contribution of content and strain, the analysis was conducted on series of pseudomorphic and relaxed epitaxial layers with a Sn content in the 5-17at.% range. All vibrational modes display qualitatively the same behavior as a function of content and strain, viz. a linear downshift as the Sn content increases or the compressive strain relaxes. Simultaneously, Ge-Sn and Ge-Ge peaks broaden, and the latter becomes increasingly asymmetric. This asymmetry, coupled with the peak position, is exploited to implement an empirical approach to accurately quantify the Sn composition and lattice strain from Raman spectra.Understanding the behavior of different vibrational modes in a semiconductor is of paramount importance to probe its crystal phase and symmetry, composition, lattice strain, isotopic content, electronic and phononic properties. [1][2][3] In this regard, Raman scattering spectroscopy has thus become an ubiquitous characterisation technique as information-rich spectra are acquired from straightforward and non-destructive measurements. Therefore, it is commonly used to evaluate the chemical composition and lattice properties of, for instance, group-IV semiconductors such as strained Si, 4-6 strained Ge, 7-10 SiGe, [11][12][13][14] and GeSn layers. [15][16][17][18][19][20][21][22][23][24][25] The latter are particularly of growing interest because of their relevance to Si-compatible light emission and detection applications in the short-and mid-wavelength infrared, [26][27][28][29][30][31][32][33][34][35] which can lead to the integration of optoelectronic and photonic circuits on complementary metal-oxide-semiconductor (CMOS) platforms. [36][37][38] Previous reports on the vibrational modes of GeSn mainly focused on Ge-Ge longitudinal optical (LO) mode as the analyses relied on the use of 488 nm 15,16 or 532 nm 18-24 excitation lines. Under these conditions, the signal-to-noise ratio is too low to clearly distinguish Sn-related vibrational modes in the vicinity of the more prominent Ge-Ge LO peak. This also applies to the study of ternary SiGeSn semiconductors. [39][40][41] When using a 633 nm excitation laser, the signal-tonoise ratio is significantly enhanced, thus allowing a clear distinction of Ge-Ge and Ge-Sn modes, in addition to other features such as disorder-activated (DA) and Sn-Sn like modes. This higher sensitivity is attributed to the increase in Raman scattering cross section when the excitation wavelength becomes close to the material's E1 gap. 39,42 Oehme et al. 25 and D'Costa et al. 17 provided a quantitative description of the evolution of peak positions as a function of the composition. However, in these studies, the investigated sampl...

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“…The formation of 3D Ge 1−x Sn x VW islands has been observed on various substrates 19,20 including biaxial CaF 2 (111) nanorods. 8 For a more in-depth comparison of the films' morphologies, 8 μm by 8 μm AFM images were used to calculate several roughness parameters. We analyzed the two-dimensional height-height correlation function, HĲr) to extract vertical surface width (or RMS roughness in the surface normal direction), ω, lateral correlation length, ξ, and roughness exponent, α.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, Sn has been shown to serve as a surfactant, lowering the temperature needed for Ge crystallization by increasing the diffusion of Ge adatoms, thus the energy costs of producing Ge films can be reduced by alloying with Sn. 8 This is done at no cost to the films' electrical properties because Sn and Ge are in the same chemical group. As a result, Ge 1−x Sn x films have demonstrated potential for application in cost-effective optoelectronics.…”

Section: Introductionmentioning

confidence: 99%

Orientation epitaxy of Ge_1−xSn_xfilms grown on single crystal CaF₂substrates

Littlejohn

Zhang

et al. 2016

CrystEngComm

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Ge 1−x Sn x films were grown via physical vapor deposition below the crystallization temperature of Ge on single crystal ( 111) and ( 100) CaF 2 substrates to assess the role of Sn alloying in Ge crystallization. By studying samples grown at several growth temperatures ranging from 250 °C to 400 °C we report temperaturedependent trends in several of the films' properties. X-ray diffraction theta vs. two-theta (θ/2θ) scans indicate single orientation Ge 1−x Sn x (111) films are grown on CaF 2 (111) substrates at each temperature, while a temperature-dependent superposition of ( 111) and ( 100) orientations are exhibited in films grown on CaF 2 (100) above 250 °C. This is the first report of (111) oriented Ge 1−x Sn x grown on a (100) oriented CaF 2 substrate, which is successfully predicted by a superlattice area matching model. These results are confirmed by X-ray diffraction pole figure analysis. θ/2θ results indicate substitutional Sn alloying in each film of about 5%, corroborated by energy dispersive spectroscopy. Additionally, morphological and electrical properties are measured by scanning electron microscopy, atomic force microscopy and Hall mobility measurements and are also shown to be dependent upon growth temperature.

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Metal-enhanced Ge_1−xSn_x alloy film growth on glass substrates using a biaxial CaF₂ buffer layer

Abstract: The Ge1−xSnx(111) alloy formation process at the early stage and later stage of Ge deposition on a biaxial Sn/CaF2 (capping layer + NR)/glass substrate at an elevated growth temperature.

Cited by 8 publications

References 33 publications

Tuning the Phase and Optical Properties of Ultrathin SnS_x Films

Tuning the Phase and Optical Properties of Ultrathin SnS_x Films

Decoupling the effects of composition and strain on the vibrational modes of GeSn semiconductors

Orientation epitaxy of Ge_1−xSn_xfilms grown on single crystal CaF₂substrates

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Metal-enhanced Ge1−xSnx alloy film growth on glass substrates using a biaxial CaF2 buffer layer

Abstract: The Ge1−xSnx(111) alloy formation process at the early stage and later stage of Ge deposition on a biaxial Sn/CaF2 (capping layer + NR)/glass substrate at an elevated growth temperature.

Cited by 8 publications

References 33 publications

Tuning the Phase and Optical Properties of Ultrathin SnSx Films

Tuning the Phase and Optical Properties of Ultrathin SnSx Films

Decoupling the effects of composition and strain on the vibrational modes of GeSn semiconductors

Orientation epitaxy of Ge1−xSnxfilms grown on single crystal CaF2substrates

Contact Info

Product

Resources

About

Metal-enhanced Ge_1−xSn_x alloy film growth on glass substrates using a biaxial CaF₂ buffer layer

Tuning the Phase and Optical Properties of Ultrathin SnS_x Films

Tuning the Phase and Optical Properties of Ultrathin SnS_x Films

Orientation epitaxy of Ge_1−xSn_xfilms grown on single crystal CaF₂substrates