Amorphous In–Ga–Zn–O Thin Film Transistor Current-Scaling Pixel Electrode Circuit for Active-Matrix Organic Light-Emitting Displays

Chen, Charlene; Abe, Katsumi; Fung, Tze Ching; Kumomi, Hideya; Kanicki, Jerzy

doi:10.1143/jjap.48.03b025

Cited by 34 publications

(26 citation statements)

References 16 publications

(20 reference statements)

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“…Although both backplane technologies are used widely, the threshold voltage of a-Si:H TFTs shifts seriously from their initial value as a result of the electrical stress caused by charge trapping and dangling bond creation. The threshold voltage of LTPS TFTs differs among pixels due to the random distribution of grain boundaries in the polysilicon material, resulting in a non-uniform gray-scale over the display area [5,6]. Consequently, TFTs based on other semiconductor materials have been evaluated as an alternative approach to realizing reliable, high-resolution and low cost AMOLEDs [7].…”

Section: Introductionmentioning

confidence: 99%

Pixel Circuit with Threshold Voltage Compensation using a-IGZO TFT for AMOLED

Lee¹,

Hwang²,

Bae³

2014

JSTS:Journal of Semiconductor Technology and Science

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Abstract-A threshold voltage compensation pixel circuit was developed for active-matrix organic light emitting diodes (AMOLEDs) using amorphous indium-gallium-zinc-oxide thin-film transistors (a-IGZO-TFTs). Oxide TFTs are n-channel TFTs; therefore, we developed a circuit for the n-channel TFT characteristics. The proposed pixel circuit was verified and proved by circuit analysis and circuit simulations. The proposed circuit was able to compensate for the threshold voltage variations of the drive TFT in AMOLEDs. The error rate of the OLED current for a threshold voltage change of 3 V was as low as 1.5%.

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Section: Introductionmentioning

confidence: 99%

Pixel Circuit with Threshold Voltage Compensation using a-IGZO TFT for AMOLED

Lee¹,

Hwang²,

Bae³

2014

JSTS:Journal of Semiconductor Technology and Science

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“…Both hydrogenated amorphous silicon (a-Si:H) TFT and low-temperature polycrystalline silicon (LTPS) TFT are not suitable for the scheme, owing to the low mobility and poor uniformity respectively. On the other hand, IGZO TFTs have the high mobility, excellent uniformity and good stability [5]. The device sizes in the sensor circuit can be small enough to decrease parasitic capacitance if IGZO TFTs are used.…”

Section: Introductionmentioning

confidence: 99%

An IGZO TFT based in-cell capacitance touch sensor

Liao

Leng

et al. 2012

2012 IEEE 11th International Conference on Solid-State and Integrated Circuit Technology

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An in-cell active matrix capacitive touch sensor using IGZO TFT is proposed in this paper. The sensor does not need touch deformation, complicated detection mechanisms or extra components. In the sensor, touching events are identified as capacitive coupling between internal detection electrodes and touch objects. Then the coupling can be converted to voltage signal and amplified. TFT sizes are decreased for the high mobility and good uniformity of IGZO, which result in a significantly improved accuracy. A capacitance with the order of 1 fF caused by the coupling could be detected and converted to an adequate output voltage signal.

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“…A typical current-controlled active-matrix circuit, which controls individual OLED or LCD pixels, has four TFTs and two capacitors. [3,7,8] Thus, a smaller TFT area is required for achieving both higher resolutions and higher pixel fill factor, which is defined as the ratio of the light emitting area over the total area of the pixel. Another important motivation for scaling TFT sizes is that the allowed pixel size decreases as the number of PPI increases, which is critical for future high resolution mobile applications such as the use of flexible displays for point-of-care medical diagnostic testing.…”

mentioning

confidence: 99%

Wavy Architecture Thin‐Film Transistor for Ultrahigh Resolution Flexible Displays

Hanna

Kutbee

Subedi

et al. 2017

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pixel receives a charge, through a driving TFT, and thus no interference comes from neighboring pixels. [3] As a result, the resolution of active-matrix-based displays can be dramatically increased in comparison with passive matrix displays. The current market dominant product of full high definition AM-LCDs has pixel numbers around three millions (1920 × 1080 × 3(RGB)). [4] Future 8K displays are expected to have more than 33.2 megapixels (4320 × 7680 × 3(RGB)), more than 300 Pixels Per Inch (PPI), and a fast frame rate (>240 Hz) in order to suppress the motion blur effect at such high resolution. [5] The essential requisite for achieving these features is a high fieldeffect mobility, µ, in TFTs. For example, 8K displays switching at 240 Hz frame rate demand field-effect mobility around 10-20 cm 2 (V s) −1 , and even higher values are desired for future displays. [6] This is because a higher µ induces a higher drain current, thus enabling the TFTs to switch faster and/or occupy a smaller pixel area. A typical current-controlled active-matrix circuit, which controls individual OLED or LCD pixels, has four TFTs and two capacitors. [3,7,8] Thus, a smaller TFT area is required for achieving both higher resolutions and higher pixel fill factor, which is defined as the ratio of the light emitting area over the total area of the pixel. Another important motivation for scaling TFT sizes is that the allowed pixel size decreases as the number of PPI increases, which is critical for future high resolution mobile applications such as the use of flexible displays for point-of-care medical diagnostic testing. [9] For example, the pixel size for 500 PPI is only 50.8 × 16:9 µm 2 . [4] Hence, it is imperative that the TFT size be scaled down along with the pixel size to be fitted inside such a small pixel area.Amorphous Oxide Semiconductors have been excellent TFT channel material candidates for future large-area FPD since their typical field-effect mobility values for n-type oxides have been in the range of 10 cm 2 (V s) −1 for indium gallium zinc oxide (InGaZnO-or popularly IGZO)-based devices, and 20 cm 2 (V s) −1 for indium (In) rich films, which are within the required range for future 8K displays. [10] However, in order to reduce the area occupied by TFT circuitry, gate length scaling has been the traditional route of downsizing TFT area. [11][12][13] Various studies have been conducted to study gate length scaling effects on n-type oxides such as ZnO, [14] InGaZnO, [4,15] A novel wavy-shaped thin-film-transistor (

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Amorphous In–Ga–Zn–O Thin Film Transistor Current-Scaling Pixel Electrode Circuit for Active-Matrix Organic Light-Emitting Displays

Cited by 34 publications

References 16 publications

Pixel Circuit with Threshold Voltage Compensation using a-IGZO TFT for AMOLED

Pixel Circuit with Threshold Voltage Compensation using a-IGZO TFT for AMOLED

An IGZO TFT based in-cell capacitance touch sensor

Wavy Architecture Thin‐Film Transistor for Ultrahigh Resolution Flexible Displays

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