電化學製備硫化鋅結構及其光學性質

硫化鋅是ㄧ個n型寬能隙直接半導體(室溫Eg=3.7eV)，非常適合應用於異質接面太陽能電池的緩衝層或是透光層。本文藉由電化學沈積法在透明導電玻璃上成長硫化鋅。在硫酸鋅和硫代硫酸鈉的電解液中，利用脈衝電化學製程(pulsed electrochemical deposition, PECD)，控制在不同電位分別做氧化或還原的反應。實驗結果發現，在陰極還原電位固定在-1.2V(vs. SCE)下，陽極氧化電位由-0.5V~-0.8V變化，氧化時間固定在4秒，可發現陽極氧化電位對鍍層表面形貌及結晶性有重大的影響。另外，陽極氧化電位-0.7V(vs. SCE)製備的鍍層較接近計量比成分。當陽極氧化時間由4秒增加為9秒時，對鍍層的表面形貌及光學性質影響不大。當電解液pH高於4時，會形成氫氧化鋅的沈積，但pH小於3時又會造成氫氣泡的形成，降低薄膜的性質，所以電解液中pH值是扮演一個很重要的角色。最後，將試片作進行300℃持溫一小時的退火處理，穿透率明顯變高，幾乎有90%穿透，但 XRD顯示出鍍層為非晶結構，從穿透圖譜看來，退火過後的鍍層很有可能為非晶結構。

關鍵字

硫化鋅；脈衝電鍍；光學性質

並列摘要

ZnS is an n-type semiconductor with a wide direct band gap (3.7eV at room temperature), and is potentially used as the window layer in heterojunction photovoltaic solar cell. In this present study, ZnS thin films were electroplated onto ITO from the electrolyte containing zinc sulfate (ZnSO4) and sodium thiosulphate (Na2S2O3) using pulsed electrochemical deposition (PECD), by which the potentials for oxidation and reduction reactions, respectively, were alternatively applied. Experimental results show that when the cathodic potential was set to be -1.2V (vs. SCE), the surface morphology and crystallinity of the deposit were markedly influenced by the anodic potentials that were varied between -0.5 and -0.8V while the duration was set to be 4 s. Moreover, the deposit plated at an anodic potential of -0.7V had the composition close to stoichiometry of ZnS. The surface morphology and optical properties of the deposit underwent insignificant change as the duration time of anodic half-cycle was increased from 4 to 9s. The pH of the solution also played an important role in the properties of ZnS films. That is, zinc hydroxides formed in the solution with pH exceeding 4, while extensive hydrogen evolution occurred in the solution with pH less than 3. Finally, transmittance of the deposit was increased to be around 90% after 1h of annealing at 300℃. The deposits after annealing displayed an amorphous structure as characterized by XRD. Transmission spectrum also revealed the annealed deposit can be amorphous.

並列關鍵字

ZnS ； pulsed electrochemical deposition ； optical properties

參考文獻

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國際替代計量

電化學製備硫化鋅結構及其光學性質

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