在此論文中，我們將研究垂直式有機薄膜電晶體。在研究過程中所有的元件都是經由影光罩(shadow mask)，以及藉由熱蒸鍍的方式來製作。我們的研究由垂直式有機電晶體中最基本的組成：蕭特基二極體開始。從厚度不同的蕭特基二極體的電流-電壓曲線，我們發現越厚的有機薄膜會阻礙電流的注入，雖然它也會使得二極體的崩潰電壓提高。再經由變溫的電流電壓曲線以及阿瑞尼士圖，我們確認了在有機材料中載子的熱促進(thermal-assisted)躍遷(hopping)傳輸機制，以及與厚度相關的陷阱能階。這可以解釋厚度所造成的低注入是由於陷阱所造成的。我們最初的垂直式有機電晶體是靜態感應電晶體(static induction transistor)，它可以提供電流的開/關比為4，以及毫安培等級的電流輸出。在靜態感應電晶體中最為關鍵的部分為其閘極的形狀，但是由於影光罩本身最小線寬的限制，使得靜態感應電晶體的特性難以更進一步的提升。因此我們採用了另一種更為可行的結構，也就是熱載子三極體(hot-carrier triode)。這種三極體藉由改變其輸入的基極電流大小，可以得到相當近似於電晶體的電流輸出特性。包含了理想的線性區以及飽和區，以及電流增益值為2.38。藉由基本的電性量測我們進一部的探討其操作的原理以及載子的傳輸機制。此種結構不需要精細複雜的光罩即可製作，且具有良好特性，故為相當適合垂直式電晶體所採用的一種結構。

In this thesis, we investigate the vertical-type organic thin film transistors (OTFTs). All the devices are fabricated through shadow masks by thermal evaporation. From the current-voltage (I-V) characteristics of thickness-varying Schottky diodes, we conclude that the thick organic layer is unfavorable to current injection though it also provides higher breakdown voltage. We confirm that the thermal-assisted carrier transport mechanism and the thickness-dependent trapping energy levels from the temperature-varying I-V characteristics and Arrhenius plots. The first vertical-type transistor we fabricate is static induction transistor, and it provides a current on/off ratio of 4 and a high current output in the order of milliampere. But the limitation of the shadow mask prohibits us from enhancing its performance. Therefore, we pursue our investigation with a promising vertical-type structure, hot-carrier triode. The devices show transistor-like characteristics which output current can be modulated by demanding different input currents on their thin metal base electrodes. They also exhibit a good current saturation with current gain of 2.38. The mechanism of operation is proposed and examined by the basic electrical measurements.

Chapter 1. Introduction
1.1. General overview of organic thin film transistors (OTFTs) and Motivation 1
1.2. Device fabrication method 3
1.3. Organization of this thesis 6

Chapter 2. Metal-organic junction: Schottky diodes.
2.1. Intrduction to materials 10
2.2. Experimental 11
2.3. Results and Discussions 13
2.4. Conclusion 18

Chapter 3. Organic static induction transistor (OSIT).
3.1. Operational principle 25
3.2. Experimental 26
3.3. Results and Discussions 27
3.4. Conclusion 31

Chapter 4. Organic hot-carrier triode (HCT).
4.1. Operational principle 39
4.2. Experimental 42
4.3. Results and Discussions 43
4.4. Conclusion 47

Chapter 5. Summary. 52
References. 55

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