非晶矽氫薄膜電晶體模型開發與顯示器
驅動電路之設計

摘要目前次世代顯示器主動式有機發光二極體(AMOLED)的發展成為全球矚目的焦點，AMOLED主要雖是以低溫多晶矽(LTPS)技術為主，但a-Si:H TFT具製程穩定及良率高的優點，因此研發a-Si:H TFT驅動電路為主的小尺寸AMOLED面板仍具競爭優勢。RPI模型因無法準確萃取臨界電壓(Vt)及源極/汲極接觸電阻(Rds)將造成模擬時元件驅動電流變動。本文提出較準確的臨界電壓(Vt)及源極/汲極接觸電阻(Rds)參數萃取流程且比較各種萃取方法在實際過程中所遭遇的問題，最後以環型振盪器做為改進參數萃取模型的驗證。研究結果達成直流模型均方根誤差小於5%，交流模型在環型振盪器的驗證下小於3%的誤差。本文針對顯示器閘極驅動電路進行ELDO模擬與OLED主動式畫素電路的實際下線量測，且進一步設計與提出拔靴帶N型反相器能改善非晶矽薄膜電晶體穩定度之電路實現。另外，考量元件穩定度的加速實驗，嘗試分析偏壓時間對於臨界電壓偏移量以及次臨界擺幅的影響，結果顯示長時間的直流偏壓只會對臨界電壓偏移量造成影響，對於次臨界擺幅的影響很小。最後本論文根據不同的元件結構針對漏電流以及驅動電流的大小進行量測分析，分析結果發現當非晶矽層完全縮在閘極電極之內會增加漏電流的形成，單閘極雙通道結構的非晶矽氫薄膜電晶體有較大的驅動電流能力。

關鍵字

非晶矽薄膜電晶體；元件模型；拔靴帶N型反相器

並列摘要

ABSTRACT Active matrix organic light emitting diodes (AMOLEDs) have gained a much interesting focus in the world wide. The LTPS are widely fabricated technologies on AMOLED, but a-Si:H thin film transistors still have own stable and high yield fabrication processes. To develop a-Si:H TFTs drivers for the applications of AMOLED panels are still rival commodities.The RPI model is unable to extract parameters of Vt and Rds precisely, which results in the variation changes on simulations of device driving currents. We bring up different kinds of procedures and a better method of extracting parameters on Vt and Rds. According to the improved extracting parameter method, the ring oscillator is approved.Experimental results the DC model RMS(Root Mean-Square Error) error is smaller than 5% , AC model RMS error is smaller than 3% base on the ring oscillator. This thesis present the development of display gate driver circuit design with ELDO and measure AMOLED pixel circuit.To use and design bootstrapped n-type inverter to compensate the Vt shift. Furthermore, the threshold voltage and subthreshold swing shift of a-Si:H TFT under DC operation is discussed and measured.DC voltage stress causes a constant Vt shift ,but subthreshold swing isn’t change much.Finally,we invertigate the leakage current and driving with different device structures are discussed.The a-Si island is completely shielded by the gate electrode exhibits higher leakage current.The structure of single gate dual channel a-Si:H TFT exhibits higher driving current.

並列關鍵字

modeling ； bootstrapped n-type inverter ； a-Si:H TFT

參考文獻

[1]曾郁潔,”被動式有機發光二極體顯示器之行驅動電路設計”，中原大學電子所碩士論文

[3]Martin J. Powell,”The Physics of Amorphous-Silicon Thin Film Transistors,” IEEE Transaction on Electron Device Vol. 36, No.12, pp.2753-2763,December 1989.

[5]Hans Pfleiderer,”Elementary Ambipolar Field-Effect Transistor Model ” , IEEE Trans. On Electron Devices,vol. ED-33. No.1 , p.145, 1986.

[6]G.W.Neudeck, K.Y.Chung,and H.F.Bare,”An Accurate CAD Model for the Ambipolar a-Si:H TFT”,IEEE Trans. Electron Devices,vol. ED-34 , NO.4 , p.866, April,1987.

[7]M.Shur and M.Hack,”Physics of amorphous silicon based alloy field-effect transistors”, J.Appl.Phys.Vol.55,NO.15 May 1984.

國際替代計量

非晶矽氫薄膜電晶體模型開發與顯示器驅動電路之設計

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