不同快速退火條件對氧化鋅薄膜電晶體的特性探討

Abstract

近年來非晶態透明導電膜因具備高透光性與高電流驅動特性而受到矚目，而為了減少材料中稀有金屬的使用及提高載子遷移率的需求，以我們研究了新材料zinc oxide(ZnO)，對多晶態的ZnO電晶體進行電特性與材料特性的探討與分析。ZnO 的光學能隙高達3.37V以上，僅會吸收波段小於360nm的紫外光，在可見光的波段具有高穿透性，再者ZnO在製程上可達到低退火溫度(400℃)與具有高載子移動率等優點，所以極有潛力成為下一代的主流顯示技術。 本研究中，探討不同氧含量的薄膜做為主動層對元件特性的影響，由實驗結果得知，微量的氧能修補薄膜內的缺陷進而達到優化的效果，然而薄膜內的缺陷態卻會隨著氧含量的增加而增加，而載子移動率隨之下降，再者，此實驗中優化的元件在經過低溫退火後的最高載子移動率可達70 cm2/V.s~ 80cm2/V.s。

Recently, the thin film transistors (TFTs) with transparent amorphous conductive thin film as active layer perform higher mobility and better reliability than conventional hydrogenated amorphous silicon TFT (a-Si: H TFT).we studied the new material to ZnO TFT, discussed and analyzed the electrical characteristics and material properties of ZnO TFT. The energy bandgap of ZnO is almost 3.7eV or more, will absorb only less than 360nm wavelength ultraviolet light. The light in the visible wavelength range with high penetration and ZnO TFT can achieve low annealing temperature (400 ℃) and has high carrier mobility, etc., so it has the potential to become the next mainstream display technology. We investigated the effect of oxygen incorporation on ZnO thin film transistors. For the devices with different oxygen flow rate incorporation, the small quantity of oxygen can repair defects and optimize the characteristic, however, the trap states increase when oxygen flow rate increases, leading to the decreasing mobility. Moreover, the mobility of the optimized devices after annealing has reached 70 cm2 /V.s~ 80cm2/V.s