Location control of giant silicon grains using organic lenses

Oh, Jae Hwan; Kim, Eun Hyun; Kim, Sang Kyu; Cheon, Jun Hyuk; Son, Yong Duck; Jang, Jin

doi:10.1063/1.2140585

Cited by 6 publications

(2 citation statements)

References 16 publications

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“…The corresponding EBSD patterns indicate that the color inside of one grain is almost the same to the radial direction, indicating the crystallization takes place toward the radial direction. 10 The textures normal to the surface keep mainly ͗111͘ and ͗101͘ orientations, as can be seen in Fig. 4c.…”

Section: Methodsmentioning

confidence: 86%

A Method of Forming a Polycrystalline Si with the Biomolecule Ferritin

Kim

Kang

et al. 2006

Electrochem. Solid-State Lett.

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We studied the metal-induced crystallization of a-Si using a Ni-ferritin molecule of 7 nm diameter. The Ni-ferritin molecules were coated onto the SiN x /amorphous silicon ͑a-Si͒/buffer/glass and it was heated at 580°C for 20 h for crystallization after UV burning of the biomaterial. It was found that the grain size of poly-Si increases with decreasing the ferritin density. A grain size of ϳ220 m was achieved, and its surface roughness was 2.1 nm.Polycrystalline-Si ͑poly-Si͒ thin-film transistors ͑TFTs͒ on glass is of increasing interest for applications to high-resolution liquidcrystal displays, active-matrix organic light-emitting diodes ͑AMOLEDs͒, and system on glass ͑SOG͒ because of its high fieldeffect mobility. Common methods for crystallizing amorphous silicon ͑a-Si͒ are solid phase crystallization ͑SPC͒, excimer laser annealing ͑ELA͒, and metal-induced crystallization ͑MIC͒. 1 Of the various approaches available, Ni-mediated crystallization of amorphous silicon is one of promising techniques for large-scale manufacturing of high-performance poly-Si TFTs with low cost. This is based on the fact that NiSi 2 crystallites have the same lattice structure with Si with a very small mismatch of 0.4%. Then, the NiSi 2 crystallites which can be formed at 400°C are seeds for crystallization of a-Si. The a-Si is crystallized as a result of migration of the seeds throughout the a-Si network. 2 To improve the quality of the poly-Si, several approaches have been conducted on the crystallization of a-Si, including a capping layer on it. For example, to control the lateral growth of ELA poly-Si through lateral thermal gradients, three different patterned capping layers have been used: antireflective ͑SiO 2 ͒, heat-sink ͑SiN x ͒, and reflective ͑metal͒ capping layers. 3 We introduced a cap layer on the a-Si to reduce metal contamination and to have a clean and smooth surface. 4,5 Recently, Kirimura et al. demonstrated the biotechnology to obtain MIC poly-Si thin-films using ferritin with a Ni core ͑7 nm͒. 6 They achieved the grain size of ϳ3 m prepared by Ni-mediated crystallization with ferritin molecules.In this work, we studied the crystallization of a-Si using Niferritin molecules on silicon nitride ͑SiN x ͒ cap layers to reduce protein contamination and to obtain large-grain poly-Si thin-films. The Ni on the cap layer diffuses through the cap and forms the seeds in a-Si for crystallization. Disk-shaped grains of 220 m were achieved, which was confirmed by optical microscopy and by electron backscattered diffraction ͑EBSD͒.

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Section: Methodsmentioning

confidence: 86%

A Method of Forming a Polycrystalline Si with the Biomolecule Ferritin

Kim

Kang

et al. 2006

Electrochem. Solid-State Lett.

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“…Poly-Si made by metal-induced crystallization with a cap layer ͑MICC͒ on a-Si layer can reduce metal contamination. 6,7 The Niinduced lateral crystallization ͑Ni-MILC͒ poly-Si TFT suffers from high leakage currents because Ni atoms stay in the channel region after the crystallization. 8,9 The Ni concentration in the MILC region is typically ϳ0.08 atom % by secondary ion mass spectroscopy ͑SIMS͒ analysis, 10 which induces the leakage currents related with Ni atoms.…”

mentioning

confidence: 99%

Effect of Ni Thickness on Off-State Currents of Poly-Si TFTs Using Ni-Induced Lateral Crystallization of Amorphous Silicon

Oh¹,

Kim²,

Cheon³

et al. 2009

Electrochem. Solid-State Lett.

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We have studied the effect of metal thickness for the metal-induced lateral crystallization ͑MILC͒ of a-Si on the off-state currents of poly-Si thin-film transistors ͑TFTs͒. It is found that they decrease with decreasing the Ni thickness for MILC. The Ni-MILC poly-Si TFT with the Ni area density of 1.4 ϫ 10 14 cm −2 exhibited a field-effect mobility of 53.5 cm 2 /Vs and minimum leakage current of 0.44 pA/m at V ds = −10 V. However, the off-state current is 6.6 pA/m when the Ni density is 9.2 ϫ 10 15 cm −2 , corresponding to the average Ni thickness of 10 Å. It is concluded that the average Ni thickness for MILC should be less than 0.79 Å to have low off-state currents from our experimental data.Polycrystalline silicon ͑poly-Si͒ thin-film transistors ͑TFTs͒ are of increasing interest for an integrated active matrix liquid-crystal displays ͑AMLCDs͒ and integrated active-matrix organic lightemitting diodes ͑AMOLEDs͒. 1 Low-cost manufacturing technology of high-quality poly-Si TFTs over a large area is a key issue of applying low-temperature poly-Si ͑LTPS͒ to AMOLEDs and AMLCDs. 2,3 A common method for the poly-Si on glass is excimer laser annealing of a-Si, 4 but it still has some issues such as nonuniformity over large areas and high manufacturing cost. 5 Ni-mediated crystallization of a-Si is of increasing interest for low-cost production and uniform poly-Si layers on glass. However, the applications of Ni-mediated lateral crystallization of a-Si to TFTs have a critical issue because the off-state leakage currents are mostly high.The leakage current of poly-Si LTPS TFTs can be reduced by reducing both defect density and Ni density in the channel region. Poly-Si made by metal-induced crystallization with a cap layer ͑MICC͒ on a-Si layer can reduce metal contamination. 6,7 The Niinduced lateral crystallization ͑Ni-MILC͒ poly-Si TFT suffers from high leakage currents because Ni atoms stay in the channel region after the crystallization. 8,9 The Ni concentration in the MILC region is typically ϳ0.08 atom % by secondary ion mass spectroscopy ͑SIMS͒ analysis, 10 which induces the leakage currents related with Ni atoms. 11 Note that the leakage current does not depend on the Ni concentration in the poly-Si when Ni density is less than 1 ϫ 10 14 cm −2 , corresponding to bulk concentration of 2.5 ϫ 10 19 cm −3 ͑0.05%͒. 12 In our previous report, 13 disk-shaped grains of 42 m in poly-Si were achieved by silicide-mediated crystallization of a-Si using a thin Ni layer of 2.43 ϫ 10 14 cm −2 . The seeds can be formed by the aggregation of NiSi 2 and the grain shape is cylindrical due to diskshaped grain growth. 14 It is found that the grain size decreases with increasing the Ni density on the a-Si for metal-induced crystallization ͑MIC͒.In this work, we have studied the effect of Ni thickness for MILC on the performance of poly-Si TFTs. The Ni density was controlled from 3.4 ϫ 10 13 to 9.2 ϫ 10 15 cm −2 , corresponding to the average thickness of 0.037-10 Å, for MILC of a-Si. The a-Si was crystallized at 580°C. Experimental Fig...

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Inverse staggered poly-Si thin-film transistor with non-laser crystallization of amorphous silicon

Ahn

Kang

et al. 2008

Solid-State Electronics

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Location control of giant silicon grains using organic lenses

Cited by 6 publications

References 16 publications

A Method of Forming a Polycrystalline Si with the Biomolecule Ferritin

A Method of Forming a Polycrystalline Si with the Biomolecule Ferritin

Effect of Ni Thickness on Off-State Currents of Poly-Si TFTs Using Ni-Induced Lateral Crystallization of Amorphous Silicon

Inverse staggered poly-Si thin-film transistor with non-laser crystallization of amorphous silicon

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