Surface roughness effects in laser crystallized polycrystalline silicon

McCulloch, D.J.; Brotherton, S. D.

doi:10.1063/1.113902

Cited by 62 publications

(42 citation statements)

References 5 publications

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“…Released hydrogen evaporates from the silicon melt, causing surface roughness. 36 Different techniques have been utilized for controlled evolution of hydrogen. Gaussian beam profiles used for these experiments are reported to be an efficient means of systematic evolution of hydrogen, due to the lower-energy preceding edge.…”

Section: Dehydrogenationmentioning

confidence: 99%

Thickness dependence of properties of excimer laser crystallized nano-polycrystalline silicon

Adikaari¹,

Silva²

2005

Journal of Applied Physics

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Excimer laser crystallization is used to produce layered nanocrystalline silicon from hydrogenated amorphous silicon, using a partial melting process. Three types of hydrogenated amorphous silicon samples, 100, 300, and 500 nm thick, were laser treated in order to investigate the changes to the structural, optical, and electrical properties as a function of amorphous silicon thickness with excimer laser crystallization. The resulting nanocrystalline thin films were characterized using Raman spectroscopy, optical absorption measurements, atomic force microscopy, forward recoil spectrometry, and current-voltage measurements. The relationship of crystalline volume and laser energy density was established, along with the behavior of the optical gap and its relationship to hydrogen content. Surface roughness effects are discussed in the context of photovoltaic applications. The effect of increased mobility on photoconductivity after excimer laser crystallization is also examined.

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Section: Dehydrogenationmentioning

confidence: 99%

Thickness dependence of properties of excimer laser crystallized nano-polycrystalline silicon

Adikaari¹,

Silva²

2005

Journal of Applied Physics

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“…The hillocks are generated by a positive feedback effect between the beam-induced periodic surface roughness pattern and the interference in subsequent pulses (McCulloch & Brotherton, 1995). Another feature of ELC is that μ FEn is considerably higher than that of SPC.…”

Section: Excimer-laser Crystallizationmentioning

confidence: 99%

Oriented Lateral Growth and Defects in Polycrystalline-Silicon Thin Films on Glass Substrates

Kitahara¹,

Hara²

2012

Crystallization - Science and Technology

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confidence: 99%

“…Conventionally, a Gaussian profile along the long axis of the pulse has been reported to be best suited for controlled evolution of hydrogen during crystallization. 8,9 Our previous report shows typical energy densities for crystallization with the crystalline volume and surface roughness comparisons of the resultant films for different film thicknesses. 2 Here, we report a significant reduction of crystallization laser energy density required to yield a given crystalline volume by modifying the Gaussian pulse profile, while retaining the controlled evolution of hydrogen from a-Si: H films.…”

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confidence: 99%

“…The gradual increase of energy is expected to help control the evolution of hydrogen during crystallization, which is the main advantage of using a Gaussian pulse profile. 8 Controlled evolution of hydrogen results in smoother film surfaces after crystallization, which is of importance for thin film transistor applications. The surface roughness of the laser crystallized silicon with the asymmetric pulse was estimated by atomic force microscopy over a 25 m 2 area using a Digital Instruments Dimension 3100 scanning probe microscope in atomic force microscopy mode.…”

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confidence: 99%

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Use of an asymmetric pulse profile for higher crystalline volumes from excimer laser crystallization of amorphous silicon

Adikaari

Mudugamuwa

Silva

2007

Applied Physics Letters

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An excimer laser is used to crystallize amorphous silicon on glass to nanocrystalline silicon, yielding higher crystalline volumes than reported earlier, by modifying the laser pulse profile used for crystallization at a given energy density. An asymmetric, shorter pulse profile, as opposed to the conventional Gaussian profile retains the desirable gradual leading edge of the Gaussian pulse for controlled evolution of hydrogen, while increasing the peak energy. The resultant films show an increased surface roughness along with higher crystalline volumes, which may be beneficial for photovoltaics and electron field emission cold cathodes. © 2007 American Institute of Physics. ͓DOI: 10.1063/1.2731664͔ Excimer lasers have been utilized for the crystallization of hydrogenated amorphous silicon ͑a-Si: H͒ for electronic applications 1,2 with well established crystallization physics.3-7 Excimer lasers typically operate in the ultraviolet and hence photons are absorbed by the silicon thin films within a few nanometers of the surface. Melting and solidifying occur on a nanosecond time scale, often without affecting the underlying substrate. This technique enables the use of inexpensive substrates, such as glass, which are highly preferable for low cost, large-area electronic devices. Films with adequate thickness for light harvesting crystallize in the partial melting regime.2,3 The properties of crystallized silicon depend on a number of factors, with laser pulse shape being one of the most significant. Conventionally, a Gaussian profile along the long axis of the pulse has been reported to be best suited for controlled evolution of hydrogen during crystallization. 8,9 Our previous report shows typical energy densities for crystallization with the crystalline volume and surface roughness comparisons of the resultant films for different film thicknesses.2 Here, we report a significant reduction of crystallization laser energy density required to yield a given crystalline volume by modifying the Gaussian pulse profile, while retaining the controlled evolution of hydrogen from a-Si: H films.Chemical vapor deposited 300 and 500 nm thick a-Si: H on a 100 nm thick silicon nitride, capped Corning 1737 glass was used for the experiments. The films contain 10% atomic hydrogen, as specified by the deposition facility. A KrF Lambda Physik excimer laser ͑LPX 210i͒, operating at 248 nm with a 25 ns full width at half maximum pulse duration, was used for crystallization. The a-Si: H films on glass were crystallized in vacuum, at a base pressure of 5 ϫ 10 −4 mbar, by scanning along the laser pulse. The scanning speed for the experiment was 2.5 mm s −1 with pulse repetition rate maintained at 50 Hz. Experimental details are as similar to that used for crystallization of a-Si: H with the Gaussian pulse profile in Ref. 2, for comparison purposes, apart from the laser pulse profile and maximum energy density used. A series of incremental energy densities of up to 200 mJ cm −2 per pulse was used for crystallization, with 25 mJ cm −2 increm...

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Surface roughness effects in laser crystallized polycrystalline silicon

Cited by 62 publications

References 5 publications

Thickness dependence of properties of excimer laser crystallized nano-polycrystalline silicon

Thickness dependence of properties of excimer laser crystallized nano-polycrystalline silicon

Oriented Lateral Growth and Defects in Polycrystalline-Silicon Thin Films on Glass Substrates

Use of an asymmetric pulse profile for higher crystalline volumes from excimer laser crystallization of amorphous silicon

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