TY - JOUR

T1 - Micromechanical Properties of Micro- and Nanocrystalline CVD Diamond Thin Films with Gradient Microstructures and Stresses

AU - Meindlhumer, Michael

AU - Ziegelwanger, Tobias

AU - Grau, Jakob

AU - Sternschulte, Hadwig

AU - Sztucki, Michael

AU - Steinmüller-Nethl, Doris

AU - Keckes, Jozef

PY - 2024/1/12

Y1 - 2024/1/12

N2 - Chemical vapor deposition produced diamonds attract considerable scientific and industrial interest due to their exceptional mechanical and functional properties. Here, hot filament chemical vapour deposition was used to synthesize two diamond thin films with different cross-sectional microstructure and residual stresses. Structural characterization by scanning electron microscopy, Raman spectroscopy and cross-sectional synchrotron X-ray nanodiffraction revealed different diamond morphologies. While the microcrystalline diamond film exhibits pronounced microstructural gradients expressed by the gradually increasing (i) intensities of the 111 Debye-Scherrer rings, (ii) ⟨110⟩ fibre texture sharpness, (iii) grain size and (iv) a slightly oscillating residual stress at the level of -0.5 GPa, the nanocrystalline diamond film showed no pronounced cross-sectional variation of microstructure above the nucleation zone of ~0.5 µm and a steady stress level of 0.25 GPa. In situ micromechanical cantilever bending tests revealed highly different mechanical properties of the two films. In detail, Young’s modulus of 830±53 and 459±53 GPa, fracture stress of 12.4±0.8 and 7.8±1.0 GPa and fracture toughness values of 6.9±0.4 and 3.6±0.3 MPa·m0.5 were evaluated for the micro- and nanocrystalline diamond films, respectively. In summary, this study provides valuable insights into the microstructure-residual stress correlation in micro- and nanocrystalline diamond films, especially illuminating their influence on micromechanical properties.

AB - Chemical vapor deposition produced diamonds attract considerable scientific and industrial interest due to their exceptional mechanical and functional properties. Here, hot filament chemical vapour deposition was used to synthesize two diamond thin films with different cross-sectional microstructure and residual stresses. Structural characterization by scanning electron microscopy, Raman spectroscopy and cross-sectional synchrotron X-ray nanodiffraction revealed different diamond morphologies. While the microcrystalline diamond film exhibits pronounced microstructural gradients expressed by the gradually increasing (i) intensities of the 111 Debye-Scherrer rings, (ii) ⟨110⟩ fibre texture sharpness, (iii) grain size and (iv) a slightly oscillating residual stress at the level of -0.5 GPa, the nanocrystalline diamond film showed no pronounced cross-sectional variation of microstructure above the nucleation zone of ~0.5 µm and a steady stress level of 0.25 GPa. In situ micromechanical cantilever bending tests revealed highly different mechanical properties of the two films. In detail, Young’s modulus of 830±53 and 459±53 GPa, fracture stress of 12.4±0.8 and 7.8±1.0 GPa and fracture toughness values of 6.9±0.4 and 3.6±0.3 MPa·m0.5 were evaluated for the micro- and nanocrystalline diamond films, respectively. In summary, this study provides valuable insights into the microstructure-residual stress correlation in micro- and nanocrystalline diamond films, especially illuminating their influence on micromechanical properties.

U2 - 10.1116/6.0003235

DO - 10.1116/6.0003235

M3 - Article

VL - 2024

JO - Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films

JF - Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films

SN - 0734-2101

IS - 42

M1 - 023401

ER -