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 journalArticle

33 Citations (Scopus)

Abstract

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
Volume90
Issue number25
DOIs
Publication statusPublished - 2007 Aug 2

Fingerprint

wetting
liquid crystals
alignment
F region
fluorine
carbon
ion beams
surface energy
radio frequencies
thin films

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)

Cite this

Ahn, Han Jin ; Kim, Jong Bok ; Kim, Kyung Chan ; Hwang, Byoung Har ; Kim, Jong Tae ; Baik, Hong Koo ; Park, Jin Seol ; Kang, Daeseung. / Liquid crystal pretilt angle control using adjustable wetting properties of alignment layers. In: Applied Physics Letters. 2007 ; Vol. 90, No. 25.
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Liquid crystal pretilt angle control using adjustable wetting properties of alignment layers. / Ahn, Han Jin; Kim, Jong Bok; Kim, Kyung Chan; Hwang, Byoung Har; Kim, Jong Tae; Baik, Hong Koo; Park, Jin Seol; Kang, Daeseung.

In: Applied Physics Letters, Vol. 90, No. 25, 253505, 02.08.2007.

Research output: Contribution to journalArticle

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AU - Ahn, Han Jin

AU - Kim, Jong Bok

AU - Kim, Kyung Chan

AU - Hwang, Byoung Har

AU - Kim, Jong Tae

AU - Baik, Hong Koo

AU - Park, Jin Seol

AU - Kang, Daeseung

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AB - 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.

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