介電層表面官能化對紅螢烯薄膜成長與其電晶體效能之影響

Effects of Dielectric-Surface Functionalization on the Growth of Rubrene Thin Films and Their Transistor Performance

巫宗祐(Tsung-Yu Wu)

指導教授 ： 陶雨臺 ； 楊耀文

國立清華大學/理學院/化學系/碩士(2011年)

https://doi.org/10.6843/NTHU.2011.00232

摘要

本論文藉由光學影像、原子力顯微影像、近緣X光吸收細微結構光譜及X光繞射等技術進行一系列表面官能化對rubrene成長影響的研究，其中以Octadecyltrichlorosilane(OTS)和4-phenylbutyltrichlorosilane(4-PBTS)的單層自組裝薄膜(self-assembled monolayer, SAM)修飾SiO2/n+-Si基材表面，觀察表面能量對rubrene成長的影響；另外以Langmuir-Blodgett(LB)的方式成長poly(N-dodecylacrylamide)(pDDA)薄膜來修飾SiO2/n+-Si基材表面，藉著改變pDDA薄膜層數和SiO2基板於LB槽的移動速率來調控表面形貌，以探討表面形貌及表面官能基對rubrene成長模式的影響。
透過光學影像及原子力顯微影像瞭解到，rubrene成長於平坦的表面可形成由束狀結構組成的球晶(spherulite)薄膜，束狀結構的面積隨著表面能量減少而增加。Rubrene成長於較平坦的pDDA薄膜時，可形成柱狀結構的薄膜；當增加pDDA薄膜的粗糙度時，成長出的rubrene薄膜中除了柱狀結構，也可觀察到片狀結構。透過近緣X光吸收細微結構光譜和X光繞射圖來分析不同rubrene薄膜的分子位向、氧化速率以及排列有序性。並將不同rubrene薄膜製成元件後量測電性效能，其結果顯示片狀結構的載子傳導效能最佳，量測到的最佳電洞遷移率為0.06 cm2V-1s-1，因此認為成長高晶相的rubrene薄膜，成長環境的表面形貌粗糙度相對於表面能量顯得較為重要。

關鍵字

有機場效電晶體 ； 紅螢烯

並列摘要

We investigated the effects of functionalization of dielectric surface on the growth of rubrene thin films by optical microscopy, atomic force microscopy (AFM), near-edge x-ray absorption fine structure (NEXAFS), and x-ray diffraction (XRD) techniques. We used self-assembly monolayer terminated by different functional groups, including alkyl chains with octadecyltrichlorosilane (OTS) and phenyl with 4-phenylbutyltrichlorosilane (4-PBTS) to study the influence of surface energy on the growth of vacumm-deposited rubrene thin films. Moreover, we used Langmuir-Blodgett (LB) films of poly(N-dodecylacrylamide) (pDDA), an aliphatic terminated polymer, to engineer the nanometer-structured suface by varying the layer thickness and the withdrawl speed of the substrate from the trough for the study of the influence of surface morphology on the growth of rubrene thin films.
Optical microscopy and AFM images reveal the presence of rubrene spherulites composed of dendritic structure when deposited on the flatter dielectric surface bonded with different termination of SAMs. The diameters of rubrene spherulites mostly amorphous is found to increase with the decreasing surface energy of dielectric SAM-terminated surface. For nano-structured pDDA LB films, not only rubrene of pillar form but sheet form can be observed. By analyzing the chraracteristic x-ray absorption peak of NEXAFS spectra, one can assess the molecular orientation and the degree of oxidation of rubrene of three different forms. The XRD data further establish that sheet form is due to single crystal with thin-sheet appearance and the longest axis (26.86Å) of rubrene unit cell is perpendicular to the substrate surface. The thin film transistor (TFT) fabricated from thin-sheet form exhibits the highest mobility (0.06 cm2/Vs). It is argued that the that the surface morphology seems to play more important role than surface energy in producing highly crystalline rubrene.

並列關鍵字

organic field-effect transistor ； rubrene

參考文獻

42. Maliakal, A. J.; Chen, J. Y. C.; So, W. Y.; Jockusch, S.; Kim, B.; Ottaviani, M. F.; Modelli, A.; Turro, N. J.; Nuckolls, C.; Ramirez, A. P. Chemistry of Materials 2009, 21, 5519.

13. Kelley, T. W.; Baude, P. F.; Gerlach, C.; Ender, D. E.; Muyres, D.; Haase, M. A.; Vogel, D. E.; Theiss, S. D. Chemistry of Materials 2004, 16, 4413.

48. Choi, J. M.; Jeong, S. H.; Hwang, D. K.; Im, S.; Lee, B. H.; Sung, M. M. Organic Electronics 2009, 10, 199.

21. Takeya, J.; Yamagishi, M.; Tominari, Y.; Hirahara, R.; Nakazawa, Y.; Nishikawa, T.; Kawase, T.; Shimoda, T.; Ogawa, S. Applied Physics Letters 2007, 90, 102120.

27. Briseno, A. L.; Mannsfeld, S. C. B.; Ling, M. M.; Liu, S. H.; Tseng, R. J.; Reese, C.; Roberts, M. E.; Yang, Y.; Wudl, F.; Bao, Z. N. Nature 2006, 444, 913.