Defect Reduction in Polycrystalline Silicon Thin Films by Heat Treatment with High-Pressure H<sub>2</sub>O Vapor

Sameshima, Toshiyuki; Hayasaka, Hiromi; Maki, Masahiko; Masuda, Atsushi; Matsui, Takuya; Kondo, Michio

doi:10.1143/jjap.46.1286

Cited by 23 publications

(15 citation statements)

References 10 publications

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“…A long time is necessary for reducing the defect density. Our recent study revealed that the oxygen concentration increased after high-pressure H 2 O vapor heat treatment, and that the hydrogen concentration decreased [29]. These results indicate a possibility that dangling bonds are well oxidized and oxygen atoms terminate dangling bonds at grain boundaries.…”

Section: Structural and Electrical Propertiesmentioning

confidence: 86%

Laser crystallization for large-area electronics

Sameshima

2009

Appl. Phys. A

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Laser crystallization is reviewed for the purpose of fabrication of polycrystalline silicon thin film transistors (poly-Si TFTs). Laser-induced rapid heating is important for formation of crystalline films with a low thermal budget. Reduction of electrically active defects located at grain boundaries is essential for improving electrical properties of poly-Si films and achieving poly-Si TFTs with high performances. The internal film stress is attractive to increase the carrier mobility. Recent developments in laser crystallization methods with pulsed and continuous-wave lasers are also reviewed. Control of heat flow results in crystalline grain growth in the lateral direction, which is important for fabrication of large crystalline grains. We also report an annealing method using a high-power infrared semiconductor laser. High-power lasers will be attractive for rapid formation of crystalline films over a large area and activation of silicon with impurity atoms.

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Section: Structural and Electrical Propertiesmentioning

confidence: 86%

Laser crystallization for large-area electronics

Sameshima

2009

Appl. Phys. A

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“…This energy is required for both production of passivation particles from H 2 O molecules and for their effective diffusion inside silicon. According to the literature , these particles can be, e.g. −OH, −H, and −OOH.…”

Section: Discussionmentioning

confidence: 99%

“…The best silicon electrical quality characterised by solar cell's V OC was 497 mV achieved at the temperature of 600 8C, the hydrogen pressure of 500 Pa after 15 min. [14,[20][21][22][23][24][25][26], these particles can be, e.g. ÀOH, ÀH, and ÀOOH.…”

Section: Plasma Hydrogenationmentioning

confidence: 99%

Passivation effect of water vapour on thin film polycrystalline Si solar cells

Pikna

Müller

Becker

et al. 2016

Physica Status Solidi (a)

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In this work, we investigated a passivation of both surface and bulk of polycrystalline silicon films by water vapour. To assess the passivation effect we used Suns‐VOC method to measure the open‐circuit voltage VOC of polycrystalline silicon thin film solar cells. The treatment conditions, i.e. temperature, steam pressure, duration, were systematically varied to optimise the passivation process. According to our results, there is a parameter interaction because the same passivation effect can be achieved at different treatment conditions. A sufficiently high temperature (350–450 °C) is necessary for a successful silicon passivation. The impact of this parameter cannot be replaced either by an elevated steam pressure or a prolonged exposure time. Nevertheless, the passivation effect of steam can be strengthened by an elevated steam pressure. Different gases were tested beside water vapour, e.g. H2, H2 + H2O, O2 + H2O, air, but none of them resulted in higher VOC than pure steam (360 mV from starting 220 mV). Results from Fourier transform infrared spectroscopy indicate that water vapour passivation is rather oxidation while hydrogen plays a significant supporting role in the process. We conclude that the water vapour passivation is able to passivate defects in the whole silicon volume. However, its passivation effect is not strong enough to become an adequate alternative to the plasma hydrogenation with the best result of VOC ∼497 mV. On the other hand, it provides advantage of simplicity (no vacuum system and deionised water steam as the only input). Recombination activity of defects in polycrystalline Si can be suppressed by their saturation for instance in hydrogen plasma (Si–H) or in water vapour (Si–O–Si).

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“…High-pressure H 2 O vapor heat treatment was developed to reduce the density of defect states in SiO 2 , a-Si, and poly-Si films and their interfaces [5][6][7][8][9]. H 2 O vapor molecules incorporate into those films and effectively terminate electrical active silicon dangling bonds.…”

Section: High-pressure H 2 O Vapor Heat Treatment To Silicon Filmsmentioning

confidence: 99%

Heat treatment of amorphous silicon p-i-n solar cells with high-pressure H2O vapor

Takenezawa¹,

Hasumi²,

Sameshima³

et al. 2012

Journal of Non-Crystalline Solids

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Defect Reduction in Polycrystalline Silicon Thin Films by Heat Treatment with High-Pressure H₂O Vapor

Cited by 23 publications

References 10 publications

Laser crystallization for large-area electronics

Laser crystallization for large-area electronics

Passivation effect of water vapour on thin film polycrystalline Si solar cells

Heat treatment of amorphous silicon p-i-n solar cells with high-pressure H2O vapor

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Defect Reduction in Polycrystalline Silicon Thin Films by Heat Treatment with High-Pressure H2O Vapor

Cited by 23 publications

References 10 publications

Laser crystallization for large-area electronics

Laser crystallization for large-area electronics

Passivation effect of water vapour on thin film polycrystalline Si solar cells

Heat treatment of amorphous silicon p-i-n solar cells with high-pressure H2O vapor

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Defect Reduction in Polycrystalline Silicon Thin Films by Heat Treatment with High-Pressure H₂O Vapor