在氧氣環境下使用微波及爐管退火製備P型氧化錫薄膜電晶體之比較

Abstract

近年來氧化物薄膜電晶體受到廣泛的重視與研究，因為氧化物半導體系統具備高載子遷移率與低溫成膜能力，極有潛力成為下世代透明軟性電子產品之關鍵材料。然而，目前氧化物半導體僅有N型的銦鎵鋅氧被廣泛使用，P型受限於其材料特性而技術尚未成熟，因此也缺少以氧化物薄膜電晶體製成的互補式電路。 本篇論文中，我們成功地以電子槍蒸鍍沉積氧化錫薄膜，製作出P型薄膜電晶體。我們分別使用微波及爐管在含氧氣的環境下退火來處理通道層，以實現P型氧化錫薄膜電晶體，微波退火在1200瓦的功率處理100秒即爐管退火在300度處理30分鐘的退火條件下有最好的電性，電流開關比分別為1.65×104及3.07×104，次臨界擺幅為0.93V/decade及0.485V/decade，場效遷移率為0.1581 cm2/V·s及0.2596cm2/V·s。除此之外，我們也對薄膜的材料特性作分析，利用X射線光電子能譜儀及X光繞射儀探討一氧化錫及二氧化錫在薄膜內的比例及晶相對電性、穿透度及能帶大小的影響，並且發現過多的二氧化錫退化P型特性的原因。 由實驗結果顯示，利用微波退火及爐管退火在氧氣環境下處理，皆能實現P型氧化錫的特性，電流開關比都有達先前文獻之水準，具有極佳的發展潛力。

In the recent years, thin-film transistors (TFTs) using oxide semiconductor have been attracted attention due to their merits in performance and low-temperature process, thus these materials have been regarded as a promising next-generation TFT technology for flexible electronics display. However, only n-type IGZO TFTs have great success and been widely used, and p-type oxide semiconductors which are limited by their transport properties are still far from practical applications. Thus, there are no complementary circuits that can be realized by oxide TFTs. In this thesis, we fabricated p-type SnOx TFTs using electron beam evaporation. In order to realize p-type property of the tin oxide, SnO active layers were treated with microwave annealing (MWA) and furnace annealed treatment in oxygen ambient. It was optimized at 1200W, 100sec of MWA and 300°C, 30min of furnace annealing. The on-off current ratio Ion/Ioff is 1.65×104 and 3.07×104, subthreshold swing is 0.93 V/decade and 0.485 V/decade, field-effect mobility is 0.1051 cm2/V･s and 0.2596 cm2/V･s, respectively. In addition, we used XRD and XPS analysis to discuss that the influence on electrical characteristics, transmittance and band gap from the ratio of SnO-to-SnO2 or [Sn2+]/[Sn4+]. The experiment results show that both microwave and furnace annealing in oxygen ambient could realize p-type SnOx TFTs. The electrical characteristics reach the level of previous literatures and have great potential.