氧化鋅摻鈦透明導電薄膜之性質研究

Structural, electrical and optical properties of TiO2 -doped ZnO films prepared by radio frequency magnetron sputtering

鍾政霖(Jeng-Lin Chung)

指導教授 ： 曾重仁

國立中央大學/工學院/機械工程學系/博士(2008年)

摘要

由於透明導電膜廣泛應用於光電元件中，尤其氧化鋅薄膜可以同時具有光與電性質，所以許多學者認為可以取代ITO薄膜。在本實驗以鈦摻入氧化鋅(TiO2 -doped ZnO)薄膜來研究其結構、電及光學性質。沉積TiO2 -doped ZnO薄膜在氬氣氣氛下，在較低之沉積壓力與較高之基板溫度，其結晶性排列較緊密，有較低之電阻率值為2.50 × 10-3 Ω-cm，而鈦摻雜量為1.34 wt %。TiO2 -doped ZnO薄膜在可見光區其光穿透率皆可達到80%以上，而其光能隙與載子濃度有關，其範圍為3.30~3.48 eV。為了提升元件效率，更進一步降低電阻率是必行之路，由於氫元素可以改善氧化鋅導電特性，因此藉由Ar+H2氣氛來沉積TiO2 -doped ZnO薄膜，氫氣比例為15%時，有最低之電阻率為6.50 × 10-4 Ω-cm，而鈦摻雜量為1.28 wt % ；不同氫含量比例對於TiO2 -doped ZnO薄膜之穿透率皆可達到85%以上，其能隙被寬化由3.42 eV增加至3.72 eV，隨著載子濃度增加而增加。在氫氬混合氣氛下摻鎂對於TiO2 -doped ZnO薄膜之性質分析，在340 ~ 350 之間有(002)繞射峰，隨著MgO摻雜含量增加，其(002)繞射峰強度漸漸減少；由實驗分析其電阻率隨著鎂含量增加而增加；在可見光區，光穿透率皆可達到85%以上；可以觀察到隨著鎂含量增加，其光學吸收限向著短波長方向偏移。

關鍵字

氧化鋅 ； 電阻率 ； 能隙

並列摘要

Transparent conducting oxide films have lately attracted a great deal of attention because of their properties of low electrical resistivity and high transmittance in the visible region. Impurity-doped ZnO films, with their good electrical and optical properties, are a promising alternative to replace ITO films for transparent electrode applications.
TiO2-doped zinc oxide thin films were deposited on glass substrates by radio frequency (RF) magnetron sputtering with TiO2-doped ZnO targets in an argon atmosphere. The crystalline structure of the TiO2-doped ZnO films gradually improved as the working pressure was lowered and the substrate temperature was raised. The lowest electrical resistivity for the TiO2-doped ZnO films was obtained when the Ti addition was 1.34 wt%; its value was 2.50 × 10-3 Ω-cm. The transmittance of the TiO2-doped ZnO films in the visible wavelength range was more than 80 %. The optical energy gap was related to the carrier concentration, and was in the range of 3.30-3.48 eV.
Highly conductive, transparent TiO2-doped ZnO films are grown by radio frequency (RF) magnetron sputtering in ambient hydrogen-argon (Ar+H2) gas at a temperature of 150 0C. Van de Walle has shown theoretically that hydrogen can act as a shallow donor to become a source of electrical conductivity. The lowest resistivity obtained is 6.50 × 10-4 Ω-cm with 1.28 wt% Ti and 15% H2 content in Ar. The optical transmittance for TiO2-doped ZnO films in the visible region is about 85 %. Due to the Burstein-Moss effect, the energy band gap increases with the carrier concentration.
Polycrystalline TiO2-doped ZnO films doped with MgO in ambient hydrogen-argon (Ar+H2) gas are prepared on glass substrates by RF magnetron sputtering. Increasing the Mg content from 0 to 17.75 wt% increases the electrical resistivity from 6.50×10-4 Ω-cm to the high resistivity. TiO2-doped ZnO films doped with MgO are an excellent wide band gap material, and its band gap varies with Mg content.

並列關鍵字

ZnO ； resistivity ； energy band gap

參考文獻

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