### Abstract

Elastic modulus and Poisson's ratio of diamond-like carbon (DLC) film was measured by a simple method using DLC bridges which are free from mechanical constraint of substrate. The DLC films were deposited on Si wafer by C_{6}H_{6} r.f. glow discharge at the deposition pressure 1.33 Pa. Because of the high residual compressive stress of the film, the bridge exhibited a sinusoidal displacement by removing the constraint of the substrate. By measuring the amplitude with known bridge length, we could determine the strain of the film required to adhere to the substrate. Combined with independent stress measurement by laser reflection method, this method allows calculation of the biaxial elastic modulus, E/(1-v), where E is the elastic modulus and v Poisson's ratio of the DLC film. By comparing the biaxial elastic modulus with plane-strain modulus, E/(1-v^{2}), measured by nano-indentation, we could further determine the elastic modulus and Poisson's ratio, independently. The elastic modulus, E, increased from 87 to 133 GPa as the negative bias voltage increased from 400 to 550 V. Poisson's ratio was estimated to be about 0.20 in this bias voltage range. For the negative bias voltages less than 400 V, however, the present method resulted in negative Poisson's ratio which is physically impossible. The limitation of the present method was also discussed.

Original language | English |
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Pages (from-to) | 203-208 |

Number of pages | 6 |

Journal | Materials Research Society Symposium - Proceedings |

Volume | 518 |

Publication status | Published - 1998 Dec 1 |

Event | Proceedings of the 1998 MRS Spring Symposium - San Francisco, CA, USA Duration: 1998 Apr 15 → 1998 Apr 16 |

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### All Science Journal Classification (ASJC) codes

- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering

### Cite this

*Materials Research Society Symposium - Proceedings*,

*518*, 203-208.

}

*Materials Research Society Symposium - Proceedings*, vol. 518, pp. 203-208.

**Measurement of elastic modulus and Poisson's ratio of diamond-like carbon films.** / Cho, Sung Jin; Lee, Kwang Ryeol; Eun, Kwang Yong; Ko, Dae Hong.

Research output: Contribution to journal › Conference article

TY - JOUR

T1 - Measurement of elastic modulus and Poisson's ratio of diamond-like carbon films

AU - Cho, Sung Jin

AU - Lee, Kwang Ryeol

AU - Eun, Kwang Yong

AU - Ko, Dae Hong

PY - 1998/12/1

Y1 - 1998/12/1

N2 - Elastic modulus and Poisson's ratio of diamond-like carbon (DLC) film was measured by a simple method using DLC bridges which are free from mechanical constraint of substrate. The DLC films were deposited on Si wafer by C6H6 r.f. glow discharge at the deposition pressure 1.33 Pa. Because of the high residual compressive stress of the film, the bridge exhibited a sinusoidal displacement by removing the constraint of the substrate. By measuring the amplitude with known bridge length, we could determine the strain of the film required to adhere to the substrate. Combined with independent stress measurement by laser reflection method, this method allows calculation of the biaxial elastic modulus, E/(1-v), where E is the elastic modulus and v Poisson's ratio of the DLC film. By comparing the biaxial elastic modulus with plane-strain modulus, E/(1-v2), measured by nano-indentation, we could further determine the elastic modulus and Poisson's ratio, independently. The elastic modulus, E, increased from 87 to 133 GPa as the negative bias voltage increased from 400 to 550 V. Poisson's ratio was estimated to be about 0.20 in this bias voltage range. For the negative bias voltages less than 400 V, however, the present method resulted in negative Poisson's ratio which is physically impossible. The limitation of the present method was also discussed.

AB - Elastic modulus and Poisson's ratio of diamond-like carbon (DLC) film was measured by a simple method using DLC bridges which are free from mechanical constraint of substrate. The DLC films were deposited on Si wafer by C6H6 r.f. glow discharge at the deposition pressure 1.33 Pa. Because of the high residual compressive stress of the film, the bridge exhibited a sinusoidal displacement by removing the constraint of the substrate. By measuring the amplitude with known bridge length, we could determine the strain of the film required to adhere to the substrate. Combined with independent stress measurement by laser reflection method, this method allows calculation of the biaxial elastic modulus, E/(1-v), where E is the elastic modulus and v Poisson's ratio of the DLC film. By comparing the biaxial elastic modulus with plane-strain modulus, E/(1-v2), measured by nano-indentation, we could further determine the elastic modulus and Poisson's ratio, independently. The elastic modulus, E, increased from 87 to 133 GPa as the negative bias voltage increased from 400 to 550 V. Poisson's ratio was estimated to be about 0.20 in this bias voltage range. For the negative bias voltages less than 400 V, however, the present method resulted in negative Poisson's ratio which is physically impossible. The limitation of the present method was also discussed.

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M3 - Conference article

AN - SCOPUS:0032299364

VL - 518

SP - 203

EP - 208

JO - Materials Research Society Symposium - Proceedings

JF - Materials Research Society Symposium - Proceedings

SN - 0272-9172

ER -