以氮化鋁作為介電層之五苯環有機薄膜電晶體—時效性處理與基板溫度效應研究

Pentacene-based Organic Thin Film Transistors with Aluminum Nitride Gate Dielectric - Aging and Substrate Temperature Effect

王文杰

指導教授 ： 黃振昌

國立清華大學/工學院/材料科學工程學系/碩士(2010年)

https://doi.org/10.6843/NTHU.2010.00301

摘要

本研究以氮化鋁為介電層之有機薄膜電晶體(OTFT, Organic
Thin Film Transistor)元件為基礎，研究五苯環(pentacene)有機半導體材料於介電層表面的介面性質，與五苯環沈積時基板的溫度效應
(substrate thermal effect)。將沈積完的氮化鋁薄膜做時效性處理
(aging process)可提高元件載子遷移率，時效性處理七天最高可達
1.806 cm2/Vs的水準；另外發現升高五苯環沈積時基板溫度反而使載
子遷移率下降，由室溫1.002cm2/Vs、攝氏50度0.178cm2/Vs至攝氏70
度0.058cm2/Vs，由AFM、GIXD與即時(in-situ)電性量測搭配Raman分
析，可歸納出五苯環分子堆疊角度與分子間作用力主導載子於五苯
環分子間傳導的特性，提出不同以往晶粒大小決定載子遷移率高低
的新觀點。
元件製作的方面， 本研究以反應式磁控射頻濺鍍系統( R F
reactive magnetron sputter system)製備氮化鋁介電層，並使用熱蒸鍍系統(thermal evaporation system)沈積五苯環薄膜與金屬電極，整體實驗流程不超過攝氏150度，符合有機薄膜電晶體往可撓曲顯示器發展的需求，並且載子遷移率超越非晶矽薄膜電晶體的水準，開發出以氮化鋁作為介電層之有機薄膜電晶體的潛力。

關鍵字

五苯環 ； 氮化鋁 ； 場效載子遷移率 ； 基板溫度

並列摘要

In this thesis, aluminum nitride is used as gate dielectric in organic thin film transistor, the main content can be divided into two parts: the aging effect on AlN and the substrate thermal effect during evaporation of pentacene. Taking the as-deposited AlN thin films to undergo the aging process can lead to the rise of the field effect mobility, after 7 days the highest field effect mobility can reach 1.806 cm2/Vs. In addition to the aging effect, the increase of substrate temperature during evaporation of pentacene results in the decrease of field effect mobility. As the
temperature increases from RT, 50℃ to 70℃, the field effect mobility decreases from 1.002 cm2/Vs, 0.178 cm2/Vs to 0.058 cm2/Vs. AFM and GIXD were used to analyze the material properties of pentacene/AlN. An in-situ Raman analysis was used to analyze the molecular vibration during the operation of OTFT. Different from the previous perspective where the mobility enhancement is mainly caused by enlarging the pentacene grain size, the experimental results suggest that the pentacene molecular stacking and the intermolecular interaction dominate the carrier transport properties.
The preparation of AlN thin films was applied by RF reactive magnetron sputter system, then by thermal evaporation to deposit pentacene thin films. Throughout the whole process, the temperature is under 150℃. Therefore, it is suitable for the requirement of the flexible display. Moreover, the field effect mobility surpasses the field effect mobility of a-Si TFTs, and it increases the potential of using the OTFTs with AlN dielectric.

並列關鍵字

pentacene ； AlN ； field effect mobility ； substrate temperature

參考文獻

[31] 古國欣, 五苯環在疏水性氮化鋁上的成長機制研究, 材料科學工程研究所, 2008, 國立清華大學

[1] H.-W. Zan, K.-H.Yen, P.-K. Liu, K.-H. Ku, C.-H. Chen, J. Hwang, Organic Electronics, (2007), 8, 450-454

[2] J. E. Lilienfeld, US Patent, (1930), 1745 175

Conference, Carnegie Institute of Technology, Pittsburgh, PA (1960)

[4] Facchetti A Mater. Today, (2007), 10, 28–37