Ar<sup>+</sup> beam sputtering on solid surfaces and nematic liquid crystal orientation

Sun, Zijie; Engels, J.; Dozov, I.; Durand, G.

doi:10.1051/jp2:1994115

Cited by 12 publications

(10 citation statements)

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“…The particle beam processing (PBP) is a general name of methods consisting in the oblique treatment of LC aligning substrates with a directed flux of particles (atoms, ions, electrons or mixtures thereof), which deposit on the substrate [1][2][3] or etch it [4,5]. As the result, the aligning surface becomes anisotropic and capable of LC alignment.…”

Section: Introductionmentioning

confidence: 99%

The Multimode LC Alignment on the Substrates Obliquely Treated with a Plasma Flux

Yaroshchuk

Kravchuk

Dobrovolskyy

et al. 2005

Molecular Crystals and Liquid Crystals

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We describe a variety of liquid crystal (LC) alignment modes on the aligning substrates obliquely treated with a flux of accelerated plasma from the anode layer thruster (ALT). The discharge area has a form of race track so that the generated flux contained two sheets of plasma corresponding to linear parts of the discharge. Within each ''sheet'' the intensity of flow (ion current density) is uniform in the direction parallel to the linear part of discharge. Across the ''sheet'', the intensity of flow has the Gaussian distribution. The alignment of LC with positive and negative dielectric anisotropy, De, was tested on the substrates of organic (polymers) and inorganic (glass and DLC) origin treated in static and dynamic regime (unidirectional translation perpendicularly to plasma ''sheet''). In the dynamic regime of irradiation, with the substrate moving with respect to the plasma beam, for LC with De > 0 we observed two aligning modes, with the easy axis confined to the plane of plasma incidence (mode 1) or perpendicular to this plane (mode 2). In the 1st aligning mode the LC pretilt angle is non-zero and can be varied with the incidence angle of plasma beam and the irradiation dose. With the increase of irradiation dose, the alignment transition from the 1st to the 2nd mode occurs. For LC with De < 0 only the 1st alignment mode uniform over all substrate was observed. In the static regime of irradiation, characterized by smooth distribution of the particle's flow across the sheet, two modes are clearly observed simultaneously; 2nd mode alignment occurs in central, most intensive part of flow, whileThese studies are partially supported by INTAS the periphery part shows the 1st mode. The areas of the 1st and the 2nd mode are separated with the narrow transition area showing multidomain (two-fold degenerate) LC alignment. The easy axis in these domains is turned by about AE45 with respect to the alignment direction in the 1st mode area. This sequence of the alignment transitions is observed in both LC with De > 0 and De < 0. We also describe a high-tilt alignment (87 -90 ) in the 1st mode realized on the hydrophobic polymers at the extremely low doses of plasma irradiation. The origin of the observed alignment effects is discussed.

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Section: Introductionmentioning

confidence: 99%

The Multimode LC Alignment on the Substrates Obliquely Treated with a Plasma Flux

Yaroshchuk

Kravchuk

Dobrovolskyy

et al. 2005

Molecular Crystals and Liquid Crystals

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“…Therefore, ploliimides can be substituted by the inorganic aligning layers. Recently, the technologies for creation of aligned nematic LC structures based on treatment of substrate surfaces by low energy ions, ionplasma etching and sputtering were elaborated [1][2][3][4][5][6][7][8]. Among these methods, the special attention deserves the method of cathode reactive sputtering (CRS) of aligning layer by using a direct current (diode system of sputtering) [9,10].…”

Section: Introductionmentioning

confidence: 99%

Disappearance of aligning properties of deposited SiOx films as caused by external factors

Kolomzarov¹

2006

Semicond. phys. quantum electron. optoelectron.

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Thermal and degradation stability of SiO x aligning films deposited by cathode reactive sputtering (CRS) in glow discharge plasma were investigated. It was shown that a heat treatment and other external factors initiate transformations on the surface of aligning film and provided new conditions at the interface. This leads to a change of slight axis orientation direction of LC molecules and appearance of various defects in the LC aligned structures. The technological ways to increase the aligning layer durability under influence of external factors were proposed.

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“…The PBP consists in the oblique treatment of LC aligning substrates with a directed flux of particles (atoms, ions, electrons or mixtures thereof), which deposit on the substrate [1][2][3] or etch it [4,5]. As the result, the aligning surface becomes anisotropic and capable of LC alignment.…”

Section: Introductionmentioning

confidence: 99%

“…Their procedure is based on the anisotropic etching with the ion beam. In contrast to the previous studies [4,5], IBM team uses ions of low energy, which modify only the very top layer of the aligning film. This is achieved by the use of the ion source of Kaufman type.…”

Section: Introductionmentioning

confidence: 99%

P‐83: Liquid Crystal Alignment on Substrates Treated with the Plasma Flux: Static and Dynamic Regimes of Irradiation

Yaroshchuk

Kravchuk

Dobrovolskyy

et al. 2004

Symp Digest of Tech Papers

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In this paper, we present the new results related to LC alignment on the substrates obliquely treated with a “sheet” of accelerated Ar+ plasma generated by an anode layers thruster (ALT). The substrates of organic (polymers) and inorganic (glass, DLC, SiO2, etc.) origin were treated with the plasma flux in static and dynamic regime (unidirectional translation perpendicularly to plasma “sheet”). For LCs with Δ∍<0, in both regimes, we observed two aligning modes, with the easy axis confined to the plane of plasma incidence (mode 1) or perpendicular to this plane (mode 2). In the 1st aligning mode the LC pretilt angle is not equal to zero and can be varied with the incidence angle of plasma beam and the irradiation dose. The uniformity of pretilt angle is better in the dynamic regime. With the increase of irradiation dose, the alignment transition from the 1st to the 2nd mode occurs. For the LC mixtures with Δ∍<0, used for VA LCD, only the 1st mode alignment (uniform over the whole substrate) is realized. It occurs at low and even at the relatively high irradiation doses, which cause the 2nd mode alignment for the LCs with δ∍>0. The pretilt angle achieves values as high as 30° and can be controlled by the irradiation dose and by the incidence angle of plasma beam. The 2nd alignment mode is observed at high irradiation doses and only in the static regime of irradiation. It occurs in the central, most intensive part, of the plasma “sheet”, while the periphery part shows the 1st mode. The areas of the 1st and the 2nd mode are separated with the narrow transition area showing multidomain (two‐fold degenerate) LC alignment. The easy axis in these domains is turned by about ±45° with respect to the alignment direction in the 1st mode area. The alignment transition 1st mode — two‐fold degenerate alignment — 2nd mode observed for LC with δ∍<0 is quite similar to the one earlier described for vapor deposition alignment. In the dynamic irradiation regime, for both types of LC, uniform alignment on the substrates as big as 15×15 cm is realized.

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Ar⁺ beam sputtering on solid surfaces and nematic liquid crystal orientation

Cited by 12 publications

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The Multimode LC Alignment on the Substrates Obliquely Treated with a Plasma Flux

The Multimode LC Alignment on the Substrates Obliquely Treated with a Plasma Flux

Disappearance of aligning properties of deposited SiOx films as caused by external factors

P‐83: Liquid Crystal Alignment on Substrates Treated with the Plasma Flux: Static and Dynamic Regimes of Irradiation

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Ar+ beam sputtering on solid surfaces and nematic liquid crystal orientation

Cited by 12 publications

References 0 publications

The Multimode LC Alignment on the Substrates Obliquely Treated with a Plasma Flux

The Multimode LC Alignment on the Substrates Obliquely Treated with a Plasma Flux

Disappearance of aligning properties of deposited SiOx films as caused by external factors

P‐83: Liquid Crystal Alignment on Substrates Treated with the Plasma Flux: Static and Dynamic Regimes of Irradiation

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Ar⁺ beam sputtering on solid surfaces and nematic liquid crystal orientation