Effects of trap-state density reduction by plasma hydrogenation in low-temperature polysilicon TFT

Wu, I‐Wei; Lewis, A.G.; Huang, Tiao‐Yuan; Chiang, A.

doi:10.1109/55.31689

Cited by 117 publications

(44 citation statements)

References 8 publications

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“…Además no necesita de una tecnología totalmente nueva para su fabricación, sino que basta con adaptar la tecnología existente para dispositivos de Si [2]. Las características de los dispositivos fabricados a partir de Si policristalino mejoran y se degradan menos con el paso del tiempo si una vez fabricados son sometidos a un proceso de hidrogenación, por ejemplo mediante exposición a un plasma, ya que el hidrógeno pasiva los enlaces insaturados presentes en las fronteras de grano y en el interior de los granos del material [3]. Es conocida la poca tendencia que tiene el Ge a enlazarse con el hidrógeno, unas cinco veces inferior a la que tiene el Si [4,5].…”

Section: Introductionunclassified

Capas de SiGe policristalino hidrogenado y su aplicación en transistores de película delgada

Rodrı́guez¹,

Rodríguez²,

Sangrador³

et al. 2004

Bol. Soc. Esp. Ceram. Vidr.

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En este trabajo se ha caracterizado el proceso de hidrogenación en un plasma generado por resonancia ciclotrónica de electrones de capas de SiGe policristalino obtenidas mediante cristalización en fase sólida y el efecto de la hidrogenación en las características eléctricas de transistores de película delgada fabricados usando dicho material. Los procesos de hidrogenación se realizaron a 150 y 250 ºC, con duraciones de hasta 11 horas. Los espectros de transmitancia en infrarrojo muestran solamente las bandas de absorción características de los enlaces Si-H. Estas bandas indican que el hidrógeno se incorpora al material enlazándose principalmente con los átomos de silicio. Las medidas de reflectancia en el ultravioleta indican que se crea daño en la superficie de la muestra y que éste aumenta a medida que lo hace el contenido en Ge. Los transistores de película delgada con capa activa de SiGe policristalino muestran un fenómeno de degradación consistente en que la corriente que atraviesa el canal disminuye con el tiempo manteniendo fijas las condiciones de polarización. La hidrogenación de los transistores hace que la degradación sea cada vez más lenta a medida que aumenta el tiempo de proceso en plasma a temperatura constante.Palabras Clave: SiGe policristalino, hidrogenación, plasma ECR, transistor de película delgada, degradación. Hydrogenated polycrystalline SiGe films and their application in Thin Film TransistorsThe hydrogenation of polycrystalline SiGe layers, obtained by solid phase crystallization, by an electron ciclotron resonance hydrogen plasma and the influence of this hydrogenation process on the electrical characteristics of thin film transistors fabricated using this material as active layer have been studied. The hydrogenation processes were carried out at 150 and 250 ºC for several times, up to 11 hours. Infrared transmission spectra of these samples show only the absorption bands corresponding to Si-H bonds, indicating that hydrogen atoms are bonded mainly to silicon atoms. Ultraviolet reflectance measurements show that the surface damage caused by the plasma exposure increases as the Ge content of the film does. The transistors fabricated using polycrystalline SiGe films as active layer show a degradation phenomenon, consisting of a progressive decrease of the drain current at constant gate and drain bias. The degradation slows down as the hydrogenation time increases at constant temperature. SiGe, hydrogenation, ECR plasma, Thin Film Transistor, degradation. Keywords: Polycrystalline INTRODUCCIÓNLa tendencia actual en la fabricación de pantallas de cristal líquido es la integración de los transistores de control junto a los pixels de la pantalla, en lugar de situarlos en el borde de la matriz. La capa activa de los transistores es una película delgada de material semiconductor, normalmente Si, depositada sobre el sustrato vítreo usado para la fabricación de la pantalla [1]. Un material de interés para la realización de la capa activa es el SiGe policristalino obtenido por cristalización ...

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Section: Introductionunclassified

Capas de SiGe policristalino hidrogenado y su aplicación en transistores de película delgada

Rodrı́guez¹,

Rodríguez²,

Sangrador³

et al. 2004

Bol. Soc. Esp. Ceram. Vidr.

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“…As a result, these hydrogenated poly-Si TFTs showed an improvement in the device performance. 5 In the case of p-i-n type a-Si:H solar cells, it has been well demonstrated that a hydrogen plasma treatment improves the properties of the buffer layer inserted between the p and i layers. Thus, we expected a hydrogen passivation technique to be very useful to improve the performance of visible a-SiC:H-based p-i-n type TFLEDs, and applied that technique 6 using an inductively coupled plasma ͑ICP͒ apparatus, which is known to have not only a high plasma density at a relatively low pressure but also a low amount of plasma damage during the process.…”

Section: Fabricated A-sic:h-based P-i-nmentioning

confidence: 99%

Ex situ hydrogen passivation effect of visible p-i-n type thin-film light-emitting diode characteristics

Lee

Lim

1997

Journal of Applied Physics

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The effect of ex situ hydrogen passivation process on the performance of visible hydrogenated amorphous silicon carbide ͑a-SiC:H͒-based p-i-n type thin-film light-emitting diodes has been investigated. An ex situ hydrogen passivation process dramatically improved the device performance; that is, the threshold voltage decreased by about 5 V, the electroluminescence ͑EL͒ intensity increased by a factor of about 3, and the EL peak shifted toward a short wavelength from 700 to 600 nm, resulting in an increase of the brightness from 1 cd/m 2 to 35 cd/m 2 . This improvement of device performance is caused by the passivation of interface states in the p/i and i/n interfaces as well as midgap states in the luminescent active intrinsic a-SiC:H layer by hydrogen atoms. A process time dependence of the ex situ hydrogen passivation effect on the device performance also has been studied.

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“…Reduction of defects by post laser annealing is important for good TFT characteristics. Plasma hydrogenation has been widely investigated to terminate silicon dangling bonds with hydrogen atoms and reduce the density of electrically active defects [22][23][24][25]. Oxygen plasma treatment is also effective to reduce the density of defects [26].…”

Section: Structural and Electrical Propertiesmentioning

confidence: 99%

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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Effects of trap-state density reduction by plasma hydrogenation in low-temperature polysilicon TFT

Cited by 117 publications

References 8 publications

Capas de SiGe policristalino hidrogenado y su aplicación en transistores de película delgada

Capas de SiGe policristalino hidrogenado y su aplicación en transistores de película delgada

Ex situ hydrogen passivation effect of visible p-i-n type thin-film light-emitting diode characteristics

Laser crystallization for large-area electronics

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