以溶膠凝膠法製備氧化鋅鋁透明導電薄膜及光電特性研究

本研究使用溶膠凝膠法結合旋轉塗佈的方式製備透明導電薄膜，利用XRD分析薄膜的結晶特性，使用SEM與AFM觀察薄膜的表面型態及粗糙度，藉由四點探針測量薄膜之片電阻，並以UV/Vis分析材料的透光率；實驗主要分為三大部分來探討，皆以製備出高透光率、低電阻係數的薄膜為目標。第一部分為氧化鋅薄膜的製備，探討熱處理溫度、環境以及時間對其結晶特性與光電性質之影響。結果顯示當熱前處理溫度在400℃的情況下，薄膜於c軸有優良的成長取向，依序經過400℃熱前處理、500℃熱後處理、500℃燒結處理以及450℃退火處理之ZnO薄膜具有最低之片電阻值，約為0.382kΩ/□，在可見光波長範圍(400~700nm)下平均透光率可達90%，光學能隙為3.27eV。第二部分為氧化鋅鋁薄膜的製備，探討鋁所添加之比例(Al/Zn=0.25~2.0at%)對其光電特性的影響。結果顯示平均透光率在可見光波長範圍下均可達92%，鋁的添加使光學能隙由3.27eV提升至3.32eV；在鋁與鋅之原子比為0.5%時，可以得到最佳的電性，其電阻係數約為2.24 × 10-3Ω•cm，透過Scherrer方程式計算出晶粒大小約為19.3nm。最後一部分則為探討薄膜厚度及溶液之酸鹼性對摻雜0.5at%鋁之氧化鋅薄膜光電特性的影響。利用橢圓偏光儀測量薄膜的厚度，平均一層之厚度約為25nm左右，當厚度達到250nm時具有穩定之電性，其電阻係數約為3.57×10-3 Ω•cm；透過添加鹽酸將溶液調整至pH6.63具有較佳之光電特性，其電阻係數約為2.94×10-3Ω•cm，平均光穿透率在可見光波長範圍下可達95%。

關鍵字

透明導電薄膜；溶膠凝膠法；氧化鋅；氧化鋅鋁

並列摘要

In this study, transparent conductive film is prepared by sol-gel spin-coating method. The crystal structure was analyzed by using XRD. The surface morphology and roughness were observed by scanning electron microscopy and atomic force microscopy. Using the four-point probe to measure the sheet resistivity of films and utilizing the UV/VIS/NIR spectrometer to measure the transmittance of the materials. The experiment was divided into three parts. The target of this research was prepared the films with high transmittance and low resistivity. First, the zinc oxide thin films were prepared and the effects of heat treatment conditions on the optoelectronic properties were investigated. The X-ray diffraction studies revealed that thin films have high preferential c-axis orientation in the case of pre-heating temperature at 400℃. It was found that the zinc oxide thin films could achieve the minimum sheet resistivity value of 0.382kΩ/□ after the preheating, post-heating, sintering and annealing process worked at 400℃, 500℃, 500℃,450℃ respectively. The averaged transmittance in the visible light region (400~700nm) was more than 90% and the value of the optical band gap was 3.27eV. Second, by doping different amounts of aluminum (0.25at%~2.0at%) to improve the electrical conductivity of zinc oxide thin films. The experiment showed that the average transmittance in the visible light region was 92% and the optical band gap increased from 3.27eV to 3.32eV. The atom ratio of Al to zinc oxide at 0.5% could get the best electrical conduction. The electrical resistivity was as low as 2.24 × 10-3Ω•cm and the grain size was 19.3nm, which was calculated from Scherrer’s equation. Last, the effects of film thickness and pH value of solution on the optical and electrical properties of 0.5at% aluminum doped zinc oxide thin films were also discussed. The thickness of thin films was measured by ellipsometer. It was found that the average thickness of one layer is about 25nm. It had the electrical resistivity stably when the thickness of thin films deposited over 250nm. The resistivity was 3.57×10-3 Ω•cm. According to the experimental results, the solution was adjusted to pH 6.63 by adding hydrochloric acid could have the best optoelectronic properties. The resistivity was about 2.94×10-3Ω•cm and the average transmittance in the visible light region was more than 95%.

並列關鍵字

Transparent Conducting Films ； Sol-gel Method ； Zinc Oxide ； Aluminum Doping Zinc Oxide

參考文獻

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以溶膠凝膠法製備氧化鋅鋁透明導電薄膜及光電特性研究

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