Property of single-crystalline Si TFTs fabricated with μ-Czochralski (grain filter) process

Ishihara, Ryoichi; Wilt, Paul C. van der; Dijk, Barry D. van; Metselaar, J.W.; Beenakker, C.I.M.

doi:10.1117/12.482582

Cited by 10 publications

(1 citation statement)

References 12 publications

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“…Furthermore, the location-controlled grain has planar defects, which are mainly coherent 3 twin boundaries and are radially distributed from the grain filter center. It has been suggested that the defective planes that are perpendicular to the current flow direction impede the ON-current [13]. In this paper, we have fabricated TFTs with and without a grain filter and with various current flow directions.…”

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confidence: 99%

Dependence of Single-Crystalline Si TFT Characteristics on the Channel Position Inside a Location-Controlled Grain

Rana

Ishihara

Hiroshima

et al. 2005

IEEE Trans. Electron Devices

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Abstract-To obtain high-performance thin-film transistors (TFTs), a comprehensive study of the channel position of TFTs inside a location-controlled grain was carried out. The location of the grain is precisely controlled by the -Czochralski process using an excimer laser. The grain was grown from a thin Si column embedded in SiO 2 (grain filter). The characteristics of the TFTs drastically improved when the channel region was not centered above the grain filter. With TFTs whose current-flow direction is parallel to the radial direction of the grain filter, an electron mobility and subthreshold swing of 600 cm 2 V s and 0.21 V/dec respectively were obtained.

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confidence: 99%

Dependence of Single-Crystalline Si TFT Characteristics on the Channel Position Inside a Location-Controlled Grain

Rana

Ishihara

Hiroshima

et al. 2005

IEEE Trans. Electron Devices

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Microstructure characterization of location-controlled Si-islands crystallized by excimer laser in the μ-Czochralski (grain filter) process

Ishihara¹,

Danciu²,

Tichelaar³

et al. 2007

Journal of Crystal Growth

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Influence of trap states on dynamic properties of single grain silicon thin film transistors

Yan

Migliorato

Ishihara

2006

Applied Physics Letters

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The transient properties of single grain-thin film transistors ͑SG-TFTs͒ with high electron mobility have been studied. Overshoot current induced by trap states has been observed in most of the devices. A method of ac measurements has been used to investigate the trap processes. Both transient and ac measurements show that the response of some SG-TFTs with high field effect mobility is dominated by a single trap level. Bias stressing on SG-TFT can induce more trap states and thus change the ac response of the device. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2193049͔Excimer-laser crystallization of amorphous silicon films is a well-established method for producing large-grain polycrystalline silicon thin film transistors ͑poly-Si TFTs͒ on glass substrates, which makes it possible to achieve the system-on-panel active matrix liquid crystal display. 1 The poly-Si TFTs have much higher field-effect mobility, typically about 100 cm 2 / V s, compared to that of amorphous silicon TFTs. However, it is still much lower than that of metal-oxide-silicon ͑MOS͒ transistors formed on bulk Si wafers. Recently, a development in TFT technology is the fabrication of location controlled single grain-thin film transistor ͑SG-TFT͒ by the method referred to as microCzochralski or grain-filter process. [2][3][4] Since there are few or no twin boundaries in the active region of SG-TFTs, higher mobilities of SG-TFTs ͑400 cm 2 /V s͒ than standard lasercrystallized poly-Si TFT are obtained. While the static characteristics of SG-TFTs have been studied before, little work has been devoted to the dynamic properties. The dynamic properties of TFTs are very important for circuit operation. Furthermore dynamic measurements are also a good method to get the information on trap parameters, 5,6 which are needed for device simulation. In this letter, we report on the dynamic characteristics of SG-TFTs. Two methods are used: pulsed transient current measurement 5,7 and small signal ac analysis. 8 N-channel SG-TFTs employed here were fabricated inside location-controlled grains as described before. 2 The gate size is width/length= 3.21 m / 2.88 m. The gate oxide is a 162 nm thick SiO 2 deposited by the low temperature oxide ͑LTO͒ process. TFT characteristics of devices fabricate at same condition have big variation, which can be attributed to the presence of twin boundaries with different numbers and different configurations in the channel. 4 We found the field effect mobility of these devices varied from 500 cm 2 /V s down to 200 cm 2 /V s.The transient current measurement was described before. 5,7 A train of pulses was applied to the gate by an Agilent 33250A wave form generator. The source was grounded and a constant voltage ͑V DS = 0.1 V͒ was applied to the drain by a Keithley 230 voltage source. The transient current was amplified by a Keithley 428 current voltage converter and detected by a LC584AL digital oscilloscope. The output signal was averaged over 1000 periods to reduce the noise. The pulse rise time was set to 20 ns, ch...

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Property of single-crystalline Si TFTs fabricated with μ-Czochralski (grain filter) process

Cited by 10 publications

References 12 publications

Dependence of Single-Crystalline Si TFT Characteristics on the Channel Position Inside a Location-Controlled Grain

Dependence of Single-Crystalline Si TFT Characteristics on the Channel Position Inside a Location-Controlled Grain

Microstructure characterization of location-controlled Si-islands crystallized by excimer laser in the μ-Czochralski (grain filter) process

Influence of trap states on dynamic properties of single grain silicon thin film transistors

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