Palladium-Induced Lateral Crystallization of Amorphous-Germanium Thin Film on Insulating Substrate

Xie, Ruilong; Phung, Thanh Hoa; Yu, Mingbin; Oh, Sue Ann; Tripathy, S.; Zhu, Chunxiang

doi:10.1149/1.3126496

Cited by 7 publications

(6 citation statements)

References 21 publications

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“…Figure 5 shows the Raman spectra of the Ge layers with different thicknesses. 22,23 The result of the Raman measurement indicates that all the Ge layers under study are amorphous or at least present a high degree of structural disorder. 22,23 It is been reported that scattering of local transverse optical phonons leads to a broad Raman band at around 275 cm −1 .…”

Section: Modeling and Discussionmentioning

confidence: 99%

“…4 because the amorphous effect also affects the band gap significantly as discussed below. 22,23 It is been reported that scattering of local transverse optical phonons leads to a broad Raman band at around 275 cm −1 . A broad Raman band at around ϳ270 cm −1 is observed for all samples, and the situation is similar to that of amorphous Ge films.…”

Section: Modeling and Discussionmentioning

confidence: 99%

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Thickness effect on the band gap and optical properties of germanium thin films

Goh¹,

Chen²,

Sun³

et al. 2010

Journal of Applied Physics

125

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The band gap and optical properties ͑dielectric functions and optical constants͒ of Ge thin films with various thicknesses below 50 nm, which were synthesized with electron beam evaporation technique, have been determined using spectroscopic ellipsometry and UV-visible spectrophotometry. The optical properties are well described with the Forouhi-Bloomer model. Both the band gap and optical properties show a strong dependence on the film thickness. For film thickness smaller than ϳ10 nm, a band gap expansion is observed as compared to bulk crystalline Ge, which is attributed to the one-dimensional quantum confinement effect. However, a band gap reduction was observed for thickness larger than ϳ10 nm, which is explained in terms of the amorphous effect in the Ge layers.

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Section: Modeling and Discussionmentioning

confidence: 99%

Section: Modeling and Discussionmentioning

confidence: 99%

Thickness effect on the band gap and optical properties of germanium thin films

Goh¹,

Chen²,

Sun³

et al. 2010

Journal of Applied Physics

125

View full text Add to dashboard Cite

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“…MILC of Si has been extensively studied, and the preferred metal is Ni due to small lattice mismatch between NiSi 2 and Si. Similar to Si, when Ge is in contact with a suitable metal such as Cu, 15) Al, 16) Au, 17) Ni, 18,19) Co, 20) or Pd, 21) its crystallization temperature is reduced. However, compared to the number of studies on MILC of Si, fewer works have been done on Ge rich SiGe and Ge, in which the choice of seed metal is still not obvious.…”

Section: Introductionmentioning

confidence: 99%

Low Temperature Metal-Induced Lateral Crystallization of Si_1-xGe_x Using Silicide/Germanide-Forming-Metals

Phung

Xie

Tripathy

et al. 2010

Jpn. J. Appl. Phys.

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Metal-induced lateral crystallization (MILC) of Si1-x Ge x (0≤x≤1) using Ni, Co, and Pd is carried out at 375 °C. It is found that the MILC rates increase with increasing Ge fraction when Ni and Co are used; however, the rate reaches a maximum at Ge mole fraction of 0.7 for Pd induced lateral crystallization of SiGe. The difference in these two trends is due to different contributions of the three processes involved during the metal-induced crystallization. Using Ni and Co, the MILC rates of Si1-x Ge x are limited by the silicon germanide formation and diffusion process for all Ge mole fractions. While the MILC rate of Si1-x Ge x using Pd is also controlled by these two processes when x is smaller than 0.7, the rate is dominantly limited by the lattice mismatch between silicon germanide and SiGe when the Ge mole fraction is larger than 0.7. Comparing the quality of MIC Ge films induced by the three metals, crystalline Ge film induced by Co has the largest grain size and the smoothest surface. Regarding the MILC rate, Pd has a similar rate as Ni in MILC of Ge, and a much higher rate than those of Ni and Co in MILC of Si0.3Ge0.7.

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“…Focusing on the first metal group, we carried out low temperature ͑from 350 to 420°C͒ MILC of Ge using Co, Ni, and Pd as seed metals. The MILC of Ge with varied temperatures using Ni, Co, and Pd were separately reported by Kanno et al, 2 Park et al, 7,8 and Xie et al 9 In Ref. 2, which investigated the MILC of Ge using Ni, the lateral growth rates at different temperatures were reported, but the quality of the film was not mentioned.…”

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confidence: 99%

Low Temperature Metal Induced Lateral Crystallization of Ge Using Germanide Forming Metals

Phung

Xie

Tripathy

et al. 2010

J. Electrochem. Soc.

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Low temperature ͑ranging from 350 to 420°C͒ metal induced lateral crystallization of Ge using germanide forming metals Ni, Co, and Pd is performed. The lateral growth lengths and crystallized Ge films' quality are optimized when annealed at 375°C, above which self-nucleation in Ge hinders the metal induced crystallization process. At 375°C, the sample with Pd as the seed metal has the largest lateral growth length, while the sample using Co as the seed layer exhibits the largest crystal grain size. The experiments suggest that the lateral growth length is associated with the diffusivity of the metal and germanide in Ge, while the crystal quality is related to the lattice mismatch between germanide and Ge.Polycrystalline germanium ͑poly-Ge͒ on insulator and low cost substrates has many potential applications in solar cell, optoelectronics, and three-dimensional integrated circuit ͑3D-IC͒. With a small bandgap of 0.67 eV at room temperature, poly-Ge can be employed in a thin-film tandem solar cell to enhance the absorption of the IR spectrum. It can also be used in optical detectors of 1.3 and 1.55 m wavelength. Vertical transistors stacking in a 3D-IC structure is expected to lessen performance degradation due to interconnects delay and power dissipation. Poly-Ge is a promising material for active layers in this 3D-IC architecture because of their high mobilities 1 and lower crystallization temperatures as compared to Si. 2 For poly-Ge to be integrated on top of existing devices or low cost substrates in optoelectronic and integrated circuit applications, it should be crystallized at low temperature, preferably below 400°C.Crystallization of deposited amorphous Ge ͑a-Ge͒ can be performed by various techniques, three of which are often discussed: laser anneal, solid-phase crystallization, and metal induced ͑lateral͒ crystallization ͑MIC/MILC͒. While laser anneal gives a high quality Ge due to local heating without damaging the underlying layers, this technique is complex and expensive. Conversely, conventional solid-phase crystallization of Ge requires a relatively long anneal time and a high temperature of around 450-550°C. 3,4 A longer incubation time is needed for a lower anneal temperature. 5 MIC/MILC is similar to solid-phase crystallization, but in this method, metals are deposited on top of or inside Ge to enhance the crystallization of Ge, with a possible reduction of the crystallization temperature to as low as 100°C. 6 MIC and MILC are the crystallization of regions inside and outside the metal coverage, respectively. Due to the lesser metal contaminant and larger grain size in the MILC region, it is preferable over MIC.The MILC of Si has been extensively studied, and the preferred metal is Ni due to the small lattice mismatch between NiSi 2 and Si. However, fewer works were done on Ge, in which the choice of seed metal is still not obvious. Metals used in the MILC process can be categorized into two groups: the first ͑Co, Ni, Pd, etc.͒ forms a germanide and the second ͑Au, Ag, Al, etc.͒ creates a eutecti...

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Palladium-Induced Lateral Crystallization of Amorphous-Germanium Thin Film on Insulating Substrate

Cited by 7 publications

References 21 publications

Thickness effect on the band gap and optical properties of germanium thin films

Thickness effect on the band gap and optical properties of germanium thin films

Low Temperature Metal-Induced Lateral Crystallization of Si_1-xGe_x Using Silicide/Germanide-Forming-Metals

Low Temperature Metal Induced Lateral Crystallization of Ge Using Germanide Forming Metals

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Palladium-Induced Lateral Crystallization of Amorphous-Germanium Thin Film on Insulating Substrate

Cited by 7 publications

References 21 publications

Thickness effect on the band gap and optical properties of germanium thin films

Thickness effect on the band gap and optical properties of germanium thin films

Low Temperature Metal-Induced Lateral Crystallization of Si1-xGex Using Silicide/Germanide-Forming-Metals

Low Temperature Metal Induced Lateral Crystallization of Ge Using Germanide Forming Metals

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Low Temperature Metal-Induced Lateral Crystallization of Si_1-xGe_x Using Silicide/Germanide-Forming-Metals