應用化學水浴法製備AgIn5S8薄膜與其光電性質研究

本研究採用經濟、可成長大面積薄膜、操作簡單之化學水浴沉積法( Chemical Bath Deposition, CBD )，成長Ag-In-S三系列之半導體光觸媒薄膜於導電玻璃上，改變操作參數(鍍膜次數、藥劑濃度等)，以獲得有效提昇AgIn5S8半導體薄膜光電流效率之操作條件。在XRD分析中，薄膜結構會隨著硫乙醯銨濃度與鍍膜次數增加逐漸成為典型的立方型AgIn5S8。由SEM可知，反應次數與乙醯銨濃度增加，薄膜上的顆粒也會隨之越大，且薄膜厚度也會越厚。此外，由EDS元素成份分析中可得知薄膜也會因鍍膜次數增加使得S/Ag比率增加。以紫外光-可見光譜儀作薄膜吸收度測試，得薄膜之能隙值為1.77 eV；薄膜穿透度測試顯示，膜厚的增加會造成薄膜之穿透率降低。本實驗利用穿透率之數據經計算式計算後所得薄膜之折射率與消光係數，會隨著鍍膜次數與硫乙醯銨濃度之增加而下降，且由(αhυ)1/n對hυ之作圖，得薄膜能隙約1.71~1.87 eV。電性量測方面，當薄膜厚度增加時，薄膜之電阻率會隨之上升，從霍爾效應量測中得載子濃度為4.05×1014~ 6.51×1014 cm-3，其趨勢與肖特基圖譜、光電流密度量測結果趨勢一致。薄膜的平帶電位為－0.293~－0.403 V (v.s Ag/AgCl)，導帶位置為－0.517~－0.618V (v.s Ag/AgCl)，價帶位置為＋1.092~＋1.228V (v.s Ag/AgCl)。在量子效率量測中，薄膜之量子效率可達2.26 %。

關鍵字

光觸媒；薄膜；光電化學反應；半導體

並列摘要

The AgIn5S8 polycrystalline films were grown on indium-tin-oxide coated glass substrates by using chemical bath deposition. New procedures for the growth of AgIn5S8 films are presented. The solutions containing silver nitrate, indium nitrate, triethanolamine, ammonium nitrate, and thioacetamide in acidic solution were used for the growth of AgIn5S8 film electrodes. The influences of various deposition parameters on structural, optical, electrical performances of films have been investigated. The X-ray diffraction patterns of the samples demonstrates the presence of polycrystalline structures of AgIn5S8 phase in these films and show AgIn5S8 phase is the major crystal structure. The thickness, band gaps and carrier densities of these samples determined from transmittance spectra and electrochemical analysis are in the range of 650~1150 nm, 1.87~ 1.71 eV, and 4.05×1014~ 6.51×1014 cm-3, respectively. The flat band potentials of these samples are located between -0.293~ -0.403 V (v.sAg/AgCl) versus normal hydrogen electrode with the Mott- Schottky measurements. The conduction bands and valance bands of films determined from flat band potentials are in the range of -0.517~ -0.618 V (v.sAg/AgCl), and +1.092~ +1.228 V (v.sAg/AgCl). The maximum photocurrent density of samples prepared in this study with external potential kept at 3.5 V was found to be 6.0 mA/cm2 under the illumination with white light intensity kept at 100 mW/cm2.

並列關鍵字

Photoelectrodes ； X-ay diffraction ； Optical properties ； Photocurrent density

參考文獻

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應用化學水浴法製備AgIn5S8薄膜與其光電性質研究

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