Liquid crystal pretilt angle control using adjustable wetting properties of alignment layers

Han Jin Ahn, Jong Bok Kim, Kyung Chan Kim, Byoung Har Hwang, Jong Tae Kim, Hong Koo Baik, Jin Seol Park, Daeseung Kang

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)


The authors demonstrate the production of amorphous fluorinated carbon (a-C:F) thin film, with adjustable wetting properties, inducing variable liquid crystal (LC) pretilt angles. To control the surface wetting properties, they apply a dual radio frequency magnetron system with a controlled power ratio of targets. In this manner we obtain various compositional surfaces with fluorine and carbon components and adjust the surface energy with regard to the various compositions. Whereas the fluorine-rich a-C:F layer shows a preference for homeotropic (vertical) LC alignment, the carbon-rich a-C:F layer shows a planar LC alignment. To achieve uniform LC alignment with a proper pretilt angle, an accelerated Ar+ ion beam irradiates the films after the deposition process. The ion beam selectively destroys the surface bonding of the a-C : F films, yielding an intermediate pretilt angle.

Original languageEnglish
Article number253505
JournalApplied Physics Letters
Issue number25
Publication statusPublished - 2007

Bibliographical note

Funding Information:
This work was supported by the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea Government (MOST) (Grant No. R01-2006-000-11066-0) and the Korea Research Foundation Grant funded by the Korean Government (MOEHRD) (KRF-2007-013D00070). They were supported by the Brain Korea 21(BK21) fellowship from the Ministry of Education of Korea. The authors would like to thank C. Rosenblatt for useful discussions.

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)


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