Driving Schemes for a-Si and LTPS AMOLED Displays

Nathan, Arokia; Chaji, G.R.; Ashtiani, Shahin Jafarabadi

doi:10.1109/jdt.2005.858913

Cited by 234 publications

(143 citation statements)

References 25 publications

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“…Gate-bias stress effects are commonly reported in the literature for a variety of transistors, a-Si TFTs, 8 organic transistors, [9][10][11] and recently also in amorphous oxide semiconductors TFTs. [12][13][14][15] The effect has been explained as a slow trapping of charge carriers in defects of unknown origin located at the semiconductor/dielectric interface.…”

mentioning

confidence: 99%

Gate-bias stress in amorphous oxide semiconductors thin-film transistors

Lopes

Gomes

Medeiros

et al. 2009

Applied Physics Letters

227

129

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A quantitative study of the dynamics of threshold-voltage shifts with time in gallium-indium zinc oxide amorphous thin-film transistors is presented using standard analysis based on the stretched exponential relaxation. For devices using thermal silicon oxide as gate dielectric, the relaxation time is 3 ϫ 10 5 s at room temperature with activation energy of 0.68 eV. These transistors approach the stability of the amorphous silicon transistors. The threshold voltage shift is faster after water vapor exposure suggesting that the origin of this instability is charge trapping at residual-water-related trap sites. © 2009 American Institute of Physics. ͓DOI: 10.1063/1.3187532͔ Amorphous gallium-indium zinc oxide ͑GIZO͒ thin-film transistors ͑TFTs͒ have attracted attention for their possible applications to flat, flexible, and transparent displays, 1-4 especially when processed at low temperatures. However, like the other TFTs' technologies, they also suffer from a stability phenomena known as gate-bias stress. 5,6 This effect manifests itself as a continuous increase in threshold voltage ͑V th ͒ when the gate bias is kept constant over time. This limits the application of these TFTs in demanding applications, such as active matrix organic light emitting displays. The increase in V th lowers the luminance of individual pixels over time, causing display nonuniformity. 7 As an example, using current technologies several driving transistors per pixel are necessary to compensate for the V th shift. Hence, a proper understanding of the stressing mechanism is of paramount importance.Gate-bias stress effects are commonly reported in the literature for a variety of transistors, a-Si TFTs, 8 organic transistors, 9-11 and recently also in amorphous oxide semiconductors TFTs. [12][13][14][15] The effect has been explained as a slow trapping of charge carriers in defects of unknown origin located at the semiconductor/dielectric interface. 13 It is known that the current degradation is faster when the devices are exposed to atmosphere 15,16 and that the stability improves after annealing. 1 Also, it has been reported that the effects can be reduced by the insertion of a passivation layer, either between the dielectric and the semiconductor 17 or on top of the semiconductor in bottom-gate structures. 16 This work provides a quantitative study of the gate-bias stress instability as a function of temperature and environment conditions. The results allow a comparison with competing TFTs technologies. Furthermore, it also provides evidences that water vapor contamination enhances this instability. Therefore, there is no conceptual limitation for the stability of GIZO based TFTs. This is in contrast to hydrogenated amorphous silicon TFTs where the instability is caused by the creation of intrinsic defects, unsaturated valence states into which electrons are trapped.The device fabrication process has been described in detail elsewhere. 18 Briefly, the TFTs were produced with a staggered bottom gate configuration on silicon wafers, which a...

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mentioning

confidence: 99%

Gate-bias stress in amorphous oxide semiconductors thin-film transistors

Lopes

Gomes

Medeiros

et al. 2009

Applied Physics Letters

227

129

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“…Active matrix organic light-emitting diode (AMOLED) display is replacing LCD as a new generation display technology due to flexibility, brilliant colors, wide viewing angle, and fast response compared with conventional LCD [3,4]. Unlike LCD, AMOLED display consumes different power when it shows different colors due to its self-illuminating characteristic.…”

Section: Introductionmentioning

confidence: 99%

Color transformation-based dynamic voltage scaling for mobile AMOLED displays

Park

Maregn

Kim

2015

IEICE Electron. Express

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AMOLED displays have been emerged as a new technology recently but have a significant portion of the total power consumption in mobile devices. In this paper, we propose a novel approach which combines color transformation and dynamic voltage scaling (DVS) synergistically in the aspects of both power saving and visual quality. It adaptively selects an allowable perceptuality and saturation threshold based on the luminance value of an input image, then transforms the colors of image pixels and performs DVS while satisfying human visuality. To implement it, a board interfaced with a mobile AMOLED display module is developed. Experiments show that the proposed approach achieves on average 29.6% power saving for still images with high satisfaction to human visuality.

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“…Among all the backplane manufacturing technologies of AMOLED displays, low-temperature polycrystalline silicon thin-film transistors (LTPS-TFTs) are widely used for their high mobility [4,5,6]. In general, the brightness is determined by the current flowing through the OLED.…”

Section: Introductionmentioning

confidence: 99%

A novel current-biased voltage-programmed pixel circuit with low temperature polycrystalline silicon thin film transistors for AMOLED

Ding

Tian

Huang

et al. 2015

IEICE Electron. Express

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This paper presents a novel current-biased voltage-programmed pixel circuit with low temperature polycrystalline silicon thin film transistors (LTPS-TFT) for active-matrix organic light-emitting diode (AMOLED) displays. The proposed 3T1C pixel circuit features a voltage data line to program pixel, and a fixed current source to compensate for non-idealities. In addition, the aging problem of the OLED could also be alleviated by the AC driving method. The simulation results indicate that the driving current has a deviation of less than 3% for ²0.5 V threshold voltage variation. Besides, it is also demonstrated that the high driving speed can be realized by increasing the bias current.

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Driving Schemes for a-Si and LTPS AMOLED Displays

Cited by 234 publications

References 25 publications

Gate-bias stress in amorphous oxide semiconductors thin-film transistors

Gate-bias stress in amorphous oxide semiconductors thin-film transistors

Color transformation-based dynamic voltage scaling for mobile AMOLED displays

A novel current-biased voltage-programmed pixel circuit with low temperature polycrystalline silicon thin film transistors for AMOLED

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