本論文中探討在以五環素(pentacene)為主動層的有機薄膜電晶體
中，加入電極修飾層在主動層與源極/汲極的接觸效應，並且研究此電極
修飾層對元件的影響。
由於銦錫氧化物(ITO)電極和五環素的介面能障較高，因而影響載子
注入，造成元件特性不佳。因此在汲極/源極與五環素之間加入一層富勒
烯(fullerene)薄膜作為修飾層。和未經修飾的元件作比較，我們可以發
現遷移率從0.057 cm2/vs 增加到0.23 cm2/vs,最大飽和電流從8.23μA
增加到45.3μA，並且在可見光波段穿透率達到62%以上。
這是由於修飾層(富勒烯)與主動層(五環素)，會在介面形成摻雜，
使得主動層內的少數載子，被電子受體分子給搶走，進而使得五環素分
子中有更多的非定域化載子(delocalized)能夠釋放出來，因而增加載子
傳輸層的導電度。
另外，加入的有機分子於五環素表面形成保護層，避免了金屬電極
於濺鍍時， 對五環素表面直接的破壞。最後利用傳輸線模型
iv
(Transmission Line Model)量測出在線性區電流電壓和通道長度的關
係，萃取出接面電阻的部份。並且證明了加入富勒烯的元件特性比未加
入富勒烯的元件特性為佳，是由於加入富勒烯後接觸電阻下降的緣故。

This thesis discusses the interface effects of contact resistance between semiconductor
layers and source/drain electrodes of pentacene-based organic thin-film transistors (OTFTs).
While using indium tin oxide (ITO) as the source/drain electrode, the device performance
became limited because of the interface barrier between the indium tin the oxide electrode
and the pentacene layer, which caused limitations in the carrier injection.
To improve the device performance, Fullerene (C60) was used as a modification layer
inserted between the source/drain electrode and the pentacene. When comparing the devices
both with and without modification layers, we observed that maximum saturation current
increased from 8.23 μA to 45.3 μA, while the mobility increased from 0.057cm2/vs to
0.23cm2/vs. Also the normalized contact resistance decreased from 1.697*106(Ωcm) to
ii
4.454*105(Ωcm) as VGS=-10V. Furthermore, the average transmittance in the visible range
(400 to 700 nm) is as higher as 62%.
These could be attributed to fullerene diffusion into the active layer pentacene formed
doping on the surface which makes minority-carrier of pentacene pulled by strong electron
acceptor molecule ,resulting in more delocalized carriers (hole) in pentacene film and
increasing pentacene film conductivity.
In addition, the thin fullerene layer prevented the bombardment of the pentacene
molecule on the surface during source/drain electrode sputtering.
Finally, we utilized the relationship of I-V and the L channel length of the linear region
from the transmission line model to extract the contact resistance part to demonstrate that
the improvement of device performance resulted from the reduction of contact resistance.

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