熱處理氣氛對浸漬氧化銦錫薄膜特性之影響

Abstract

浸漬法（dip coating method）鍍膜後，都需要再一階段的退火熱處理，而熱處理條件對透明導電薄膜的光電特性有很大影響，尤其熱處理過程中通以氣氛處理，對薄膜導電性有非常大之影響，若通以正確的還原氣體，薄膜片電阻值（sheet resistance）甚至可以達50Ω/□以下。本研究主要探討浸漬氧化銦錫薄膜在不同氣氛下退火熱處理後，對薄膜結構與薄膜光、電性質之影響，其中深入探討還原氣體增加薄膜導電性的機制，而導電性與光學特性之間關聯也將討論；此外薄膜隨時間的老化效應（aging effect）也會加以觀察，以了解常溫下空氣中薄膜特性將如何變化。 研究結果顯示，退火過程通以還原氣氛，若氫含量增加會增加導電性，同時降低近紅外光區域的穿透率且吸收端（absorption edge）波長往短波長移動；若在含氧氣氛下退火熱處理，電阻率將隨含氧量增加而增大，其中直接在空氣中退火熱處理，有最大的電阻率。老化效應結果顯示，含氧氣氛退火熱處理的試片，在常溫下空氣中放置，電阻率均有明顯下降，放置三週後薄膜電阻率均趨於穩定；而還原氣氛中退火熱處理的試片，在常溫下空氣中放置，電阻率隨時間緩慢上升，試片穩定後其電阻率仍然較低。 所有試片都有高於87.5%之平均可見光穿透率，1%H2和2%H2試片穩定後片電阻約600Ω/□，符合觸控面板（touch panel）之應用。

Indium tin oxide （ITO） films were deposited on soda-lime glass substrates by dip coating. Post-annealing condition was an important parameter which influenced film’s structure and properties obviously. Two main issues were investigated. One part was the post-annealing done in different atmosphere. The effects of annealing atmosphere on the film structure, surface morphology, optical and electrical properties of ITO films were studied. The other was aging effect of ITO films which exposed in air at room temperature. Optical and electrical properties were measured day by day for one month. The results showed that the different annealing atmosphere influenced the carrier concentration and other properties. The carrier concentration was higher in reductive atmosphere than in annealing atmosphere with partial oxygen like air. The oxygen vacancies were eliminated by oxygen atoms from the atmosphere which contained oxygen. The resistivities of ITO films annealed in reductive atmosphere were slightly increased with days. This was because oxygen vacancies were combined with oxygen atoms from environment and decreased the carrier concentration. And oxygen atoms were leaved the films and increased the carrier concentration when annealed in atmosphere with partial oxygen. All the ITO glasses have high visible transmittance above 87.5%, and the results of the present study can be directly applied to the ITO glass for touch panels.