• 沒有找到結果。

本實驗採用 AZO/p-type Si 結構,用直流磁控濺鍍法沉積。藉由不同表 面前處理,如緩衝氧化蝕刻液 (BOE)、雙氧水 (H2O2) 及稀鹽酸 (HCl),及 及不同基板溫度下沉積 AZO 薄膜,經由物性與電性的分析,來探討不同實 驗參數對於 AZO/Si 異質接面太陽能電池的影響,歸納得到以下的結論。

TEM 圖分析得知 AZO 都是呈現柱晶狀態,並明顯的看到 AZO/Si 異 質接面的界面層,interface 厚度在 1.87~4.16 nm 之間;在矽基板以 H2O2 表 面前處理(100 nm、製程溫度 573 K) 的 interface 較薄,只有 1.87 nm;此外 由 EDS 成份分析顯示,H2O2 表面前處理,AZO 薄膜之氧原子與鋅原子含 量比例較為接近,可得到較接近計量比的 AZO 薄膜,並以太陽光源模擬器 (Solar simulate) AM1.5 測量,可獲得較佳的光電流約 1.1×10-4 A/cm2

變溫電流-電壓(I-V)量測結果分析得知,以 H2O2 表面前處理於製程溫 度 298 K 及 573 K,依熱離子發射 (thermionic emission) 理論計算蕭特基 能障高度分別為 0.23 eV 及 0.41 eV,而以電容-電壓(C-V)特性去計算蕭特 基能障高度,蕭特基能障高度分別為 1.16 eV 及 1.44 eV。這說明我們使用 熱離子發射 (thermionic emission) 理論計算出來的能障高度會被晶片表面 缺陷所影響,使得計算出來的能障高度有誤差,兩者互相對應發現有一致關 係,當溫度升高,能障值會增加,推測可能是溫度升高時,存在於 AZO/Si 異 質接面之界面態密度 (The interface state density, Dit) 變小使得陷阱輔助穿 隧 (trap-assisted tunneling) 效應減少,有效能障高度隨之變高。

IPCE 量測顯示,在可見光 400-800 nm 區段的光電轉化率,以 H2O2 表 面前處理,製程溫度為 573 K 時,在 IPCE 值上有較佳的表現,光電轉化 率約 26.6 %,且在各個波段的轉換效率均大於其他兩項處理材料於該波段 下的轉化率。

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