具有臨界電壓補償功能雙閘極IGZO TFT電路之研究

Abstract

非晶矽IGZO薄膜電晶體 (IGZO TFTs) 備受關注，因為它有幾個優點，如高載子遷移率，高透明度，製程溫度低，均勻性好。然而，臨界電壓 (Vth) 的不穩定，限制了IGZO 在電路上的應用。最近，雙閘極IGZO TFT被提出具有較好的元件特性和較穩定的臨界電壓，它的結構分別在底部和頂部各有一個閘極。 在正常的底部閘極 (bottom-gate) 的操作下，雙閘極IGZO薄膜電晶體的臨界電壓可透過頂部閘極 (top-gate) 來操控。基於這個現象，我們提出了透過頂部閘極的操作來補償臨界電壓的變異的新概念。在本篇論文中，將此新概念應用到數位緩衝器(digital buffer) 和有機發光二極體(OLED) 的畫素電路中，利用實驗的方式來驗証這個新概念。

Amorphous InGaZnO4 (IGZO) thin film transistor (TFT) has drawn great attention because it has several merits such as high mobility, high transparency, low processing temperature, and potentially good uniformity. However, the threshold voltage (Vth) instability IGZO TFT can limits its applications in the circuits. Recently, the dual-gate IGZO TFT with two gates on the bottom and the top was proposed to have better device performance and better stability of Vth after voltage stress. The threshold voltage of the TFT using the bottom-gate in its normal operation can be controlled by the top-gate. Based on this phenomenon, a new concept of using the top-gate to compensate threshold voltage variation is proposed. In this thesis, this new concept of Vth compensation is demonstrated experimentally in digital buffer and pixel circuits of active-matrix organic light-emitting diode (AMOLED).