35.1: 2.5‐in. AMOLED with Integrated 6‐Bit Gamma Compensated Digital Data Driver

Matsueda, Yojiro; Kakkad, R.; Park, Y. S.; Yoon, Han-Hee; Lee, W. P.; Koo, Jae Bon; Chung, Ho Kyoon

doi:10.1889/1.1821323

Cited by 28 publications

(15 citation statements)

References 4 publications

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“…[1][2][3] Compared to amorphous silicon ͑a-Si͒ TFTs, LTPS TFTs have a higher electron mobility and driving current. Consequently, the LTPS TFTs can integrate both the pixel array and peripheral circuits on the same glass substrate to realize a system-on-panel ͑SOP͒ display.…”

mentioning

confidence: 99%

Degradation of Low Temperature Polycrystalline Silicon Thin Film Transistors under Negative Bias Temperature Instability Stress with Illumination Effect

Lin¹,

Chen²,

Chang

et al. 2010

J. Electrochem. Soc.

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This work investigates negative bias temperature instability ͑NBTI͒ in low temperature polycrystalline silicon thin film transistors ͑LTPS TFTs͒ in a darkened and in an illuminated environment of different light intensities. Experimental results reveal that the generations of interface state density ͑N it ͒ are identical under various illuminated intensity NBTI stresses. Nevertheless, the degradation of the grain boundary trap ͑N trap ͒ under illumination was more significant than that for the darkened environment, with degradation increasing as illumination intensity increases. This phenomenon is mainly caused by the extra number of holes generated during the illuminated NBTI stress. The increased N trap degradation leads to an increase in the darkened environment leakage current. This indicates that more traps are generated in the drain junction region than from carrier tunneling via the trap, resulting in leakage current. Conversely, an increase in N trap degradation results in a decrease in the photoleakage current. This indicates that the number of recombination centers increases in the poly-Si bulk, affecting photosensitivity in LTPS TFTs.Low temperature polycrystalline silicon thin film transistors ͑LTPS TFTs͒ have been widely investigated for flat-panel applications, such as for active matrix liquid crystal displays ͑AMLCDs͒ and active matrix organic light emitting diodes. 1-3 Compared to amorphous silicon ͑a-Si͒ TFTs, LTPS TFTs have a higher electron mobility and driving current. Consequently, the LTPS TFTs can integrate both the pixel array and peripheral circuits on the same glass substrate to realize a system-on-panel ͑SOP͒ display. 4,5 Because driving circuits for LTPS TFTs are designed using the complementary metal oxide semiconductor inverter structure, the reliability of the p-channel LTPS TFTs ͓understood by such measurements as negative bias temperature instability ͑NBTI͔͒ has been an important problem and has been widely investigated and discussed. Previous studies, however, have investigated NBTI only in darkened environments 6-8 although LTPS TFTs are usually operated in illuminated environments on AMLCDs or SOP displays. Therefore, NBTI under illumination is an important issue for predicting LTPS TFT degradation. Both the illumination effect in LTPS TFTs 9,10 as well as the reliability of a-Si TFTs under illumination have previously been studied. 11 However, NBTI degradation in p-channel LTPS TFTs under illumination has not been adequately clarified.This work studies the NBTI effect of p-channel LTPS TFTs under various illumination intensities and temperatures. By analyzing the interface state density ͑N it ͒ and the grain boundary trap density ͑N trap ͒ after NBTI stresses, the results indicated that only the generation of N trap after illuminated NBTI stress is more pronounced due to the excess light-induced holes. The darkened leakage and the photoleakage currents after different NBTI stresses were also investigated. ExperimentalThe p-channel LTPS TFTs were fabricated on a glass substrate...

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mentioning

confidence: 99%

Degradation of Low Temperature Polycrystalline Silicon Thin Film Transistors under Negative Bias Temperature Instability Stress with Illumination Effect

Lin¹,

Chen²,

Chang

et al. 2010

J. Electrochem. Soc.

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“…It has become a new trend to integrate functional low temperature poli-Si TFT circuits on AM-OLED panels to make the module compact and practical [2][3] [4]. However, it is difficult to integrate analog circuits in AM-OLEDs without sacrificing image quality because OLED electro-optical characteristics is much more sensitive to the applied signals than LCD.…”

Section: System On Panelmentioning

confidence: 99%

40.1: Invited Paper: AMOLED Technology for Mobile Displays

Chung

Kim

Kristal

2006

SID Symposium Digest

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“…Low-temperature poly-Si (LTPS) TFTs have attracted much attention for pixel circuits and integrated peripheral circuits of active-matrix liquid-crystal displays (AMLCDs) and active-matrix light-emitting diodes (AMOLEDs). [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Organic light-emitting-diode (OLED) displays are currently being widely researched and investigated due to their various advantages, such as wide viewing angle, fast response time, compact simple structure, and light weight. [1][2][3][4] Activematrix driving methods are better than passive-matrix driving methods for displays with high resolution and suitable for large panel sizes.…”

Section: Introductionmentioning

confidence: 99%

Threshold‐voltage‐compensation methods for AMOLED pixel and analog buffer circuits

et al. 2006

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Abstract— New pixel‐circuit designs for active‐matrix organic light‐emitting diodes (AMOLEDs) and a new analog buffer circuit for the integrated data‐driver circuit of active‐matrix liquid‐crystal displays (AMLCDs) and AMOLEDs, based on low‐temperature polycrystalline‐silicon thin‐film transistors (LTPS‐TFTs), were proposed and verified by SPICE simulation and measured results. Threshold‐voltage‐compensation pixel circuits consisting of LTPS‐TFTs, an additional control signal line, and a storage capacitor were used to enhance display‐image uniformity. A diode‐connected concept is used to calibrate the threshold‐voltage variation of the driving TFT in an AMOLED pixel circuit. An active load is added and a calibration operation is applied to study the influences on the analog buffer circuit. The proposed circuits are shown to be capable of minimizing the variation from the device characteristics through the simulation and measured results.

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35.1: 2.5‐in. AMOLED with Integrated 6‐Bit Gamma Compensated Digital Data Driver

Cited by 28 publications

References 4 publications

Degradation of Low Temperature Polycrystalline Silicon Thin Film Transistors under Negative Bias Temperature Instability Stress with Illumination Effect

Degradation of Low Temperature Polycrystalline Silicon Thin Film Transistors under Negative Bias Temperature Instability Stress with Illumination Effect

40.1: Invited Paper: AMOLED Technology for Mobile Displays

Threshold‐voltage‐compensation methods for AMOLED pixel and analog buffer circuits

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