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

Sung Jin Cho, Kwang Ryeol Lee, Kwang Yong Eun, Dae Hong Ko

Research output: Contribution to journalConference articlepeer-review

2 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)203-208
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
Publication statusPublished - 1998
EventProceedings of the 1998 MRS Spring Symposium - San Francisco, CA, USA
Duration: 1998 Apr 151998 Apr 16

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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