| AVS 54th International Symposium | |
| Electronic Materials and Processing | Monday Sessions |
| Session EM-MoM |
| Session: | Organic Materials and Devices |
| Presenter: | S.W. Park, Yonsei University, Republic of Korea |
| Authors: | S.W. Park, Yonsei University, Republic of Korea S.H. Jung, Yonsei University, Republic of Korea J.M. Choi, Yonsei University, Republic of Korea J.M. Whang, Yonsei University, Republic of Korea J.H. Kim, Yonsei University, Republic of Korea S. Im, Yonsei University, Republic of Korea |
| Correspondent: | Click to Email |
Semiconducting organic materials have attracted much attention during the last and even this decade, because of their potentials toward low temperature-, low cost-, and flexible substrate-based electronics. The most popular organic semiconductor is pentacene which has a high field effect mobility exceeding 1 cm2/Vs in the form of a channel of a thin-film transistor (TFT). Among the promising candidate materials, rubrene is also attracting recent interests because in single crystal form it shows a very large field-effect mobility (up to 20 cm2/Vs). For practical applications, several groups have also studied crystalline thin film phase. But it has been found not easy to get a good crystalline rubrene thin film unlike the case of pentacene, although other group could obtain a good crystalline phase film through a solution-process-involving technique.1-3 We have studied the crystalline thin film fabrication by thermal evaporation, that may be more compatible with device patterning. In the previous work,4 we have obtained a rubrene thin film which has an amorphous-crystalline mixed phase on SiO2 substrate. The film thus contained crystal domains of few hundred diameters embedded in amorphous matrix. In the present work, based on our new findings, we report on how to increase the crystal domain size so that the mobility of a rubrene-TFT may be maximized on SiO2 dielectric. Initially, amorphous rubrene thin film was obtained on 200 nm-thick SiO2/Si substrate at 40 oC in a vacuum chamber by thermal evaporation but in-situ long time post-annealing at the elevated temperatures of 60 ~ 80 oC transformed the amorphous phase into crystalline. Based on an optimum condition to cover whole channel area with polycrystalline film, we have fabricated a rubrene-TFT with a relatively high field effect mobility of 0.002 cm2/Vs, on/off ratio of ~ 104 and a low threshold voltage of -10V.
1 D. Käfer and G. Witte, Phys. Chem. Chem. Phys. 7, 2850 (2005).
2 S. Seo, B. Park, and P. G. Evans, Appl. Phys. Lett. 88, 232114 (2006).
3 N. Stingelin-Stutzmann, E. Smits, H. Wondergem, C. Tanase, P. Blom, P. Smith and D. Deleeuw, Nature. Mater. 4, 601 (2005).
4 S. Park, J. Whang, J. Choi, D. Whang, M. Oh, J. Kim, S. Im, Appl. Phys. Lett. 90, 153512 (2007).