5-1 結論
本研究展示利用 PVA 高分子介電層製作於軟性薄膜電晶體的優勢，利用其低楊氏係 數及溶液製程旋塗的優越性，在不銹鋼軟性基板上，彎曲電性量測具有較低的臨限電壓 位移 0.1 V，且不影響前段閘極金屬膜薄的沉積。但由於 PVA 支鏈氫氧根的特性，在 TFT 閘極電壓來回量測下，束縛多餘載子使得電性產生位移 3.9 V，稱為遲滯現象，為本研 究的主要研究方向。
為了改善介電層遲滯現象，嘗試於 PVA 溶液內添加二氧化矽奈米粉末，使得支鏈氫 氧根吸附在二氧化矽表面，鍵結呈現穩定的狀態，藉此減少 TFT 操作時束縛載子的現象，
大幅改善電性位移為 0 V。
5-2 未來展望
在軟性薄膜電晶體的發展上，為了能在背板彎曲時依舊保有穩定的電性，改從機械 應力的角度探討 TFT 和軟性基板的關係，可以發現在彎曲曲率為正的情況下，表面的薄 膜電晶體是受到彎曲的張應力(Tension)在作用，薄膜在超過彈性限度的情況下，表面 會產生裂痕；而在彎曲曲率為負值時，壓應力(compression)會使薄膜表面和基板產生 縫隙。在這邊提出使用上下多層的構造，在原本的 TFT 上面額外覆蓋一層材料，在彎曲 時 TFT 將受到張應力和壓應力的影響，選擇適當的 TFT 位置，將使兩力互相抵消，減緩
圖 5-2-1 (a)張應力示意圖 (b)壓應力
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圖 5-2-2 多層示意圖
在彎曲時超過彈性限度的狀況。此位置可利用 Stoney formula 估計判斷，藉由上下夾 層造成相反方向的張力，在原本 TFT 結構上增加一層厚為 dp、Young`s modules 為 Yp的 保護膜，滿足(5.1)式，藉此方法來解決彎曲電性的問題。
2 2
s s p p
Y d Y d
(5.1)
另外在介電層 PVA 的遲滯討論上，原本 TFT 結構中的主動層材料為無機的 IGZO，在 使用濺鍍沉積 IGZO 時，會破壞介電層的表面，造成嚴重的閘極漏電，或是濺鍍產生額 外的電子束縛在介電層內，在這樣的製程架構下，介電層遲滯的問題會較為複雜，故可 以改採用有機的主動層材料，像是使用蒸鍍來沉積的 pentance，或是本實驗室研究的有 機材料 TiOPc 來完成，在實際說明上會更有說服力。
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