TY - JOUR

T1 - Multimethod cross-sectional characterization approaching the limits of diamond monophase multilayers

AU - Meindlhumer, Michael

AU - Grau, Jakob

AU - Sternschulte, Hadwig

AU - Halahovets, Yuriy

AU - Siffalovic, Peter

AU - Burghammer, Manfred

AU - Steinmüller-Nethl, Doris

AU - Keckes, Jozef

PY - 2024/5/13

Y1 - 2024/5/13

N2 - Chemical vapour deposited diamond draws significant scientific interest due to its wide range of mechanical and functional properties, which can be easily tuned by the applied deposition conditions. Here, hot filament chemical vapour deposition was used to synthesize four monophase multilayer diamond thin films with indi- vidual layer thickness down to ~ 300 nm. Extensive structural characterization by scanning electron microscopy and Raman spectroscopy on the cross-section confirmed the different diamond morphologies originating from the different applied process parameters of the individual sublayers, where Raman spectroscopy could give a clear distinction between nano- and microcrystalline diamond down to a layer thickness of ~ 1 μm. Cross- sectional X-ray nanodiffraction identified exclusively the diamond crystal structure throughout the cross- section of the multilayered diamond thin films. Cross-sectional phase and FWHM analysis allowed to discrimi- nate between the diamond morphologies down to ~ 500 nm, thus identifying the limitations of monophase diamond multilayers. While the microcrystalline diamond sublayers all exhibit pronounced structural gradients expressed in (i) increasing intensity of the 111 Debye-Scherrer ring, (ii) 〈110〉 fibre texture, and periodic vari- ations of (iii) grain size and (iv) residual stress, the nanocrystalline diamond sublayers showed no pronounced cross-sectional variations. In summary, the experimental results provide insights into the cross-sectional evo- lution of microstructure and residual stress and the limitations of monophase multilayered diamond thin films.

AB - Chemical vapour deposited diamond draws significant scientific interest due to its wide range of mechanical and functional properties, which can be easily tuned by the applied deposition conditions. Here, hot filament chemical vapour deposition was used to synthesize four monophase multilayer diamond thin films with indi- vidual layer thickness down to ~ 300 nm. Extensive structural characterization by scanning electron microscopy and Raman spectroscopy on the cross-section confirmed the different diamond morphologies originating from the different applied process parameters of the individual sublayers, where Raman spectroscopy could give a clear distinction between nano- and microcrystalline diamond down to a layer thickness of ~ 1 μm. Cross- sectional X-ray nanodiffraction identified exclusively the diamond crystal structure throughout the cross- section of the multilayered diamond thin films. Cross-sectional phase and FWHM analysis allowed to discrimi- nate between the diamond morphologies down to ~ 500 nm, thus identifying the limitations of monophase diamond multilayers. While the microcrystalline diamond sublayers all exhibit pronounced structural gradients expressed in (i) increasing intensity of the 111 Debye-Scherrer ring, (ii) 〈110〉 fibre texture, and periodic vari- ations of (iii) grain size and (iv) residual stress, the nanocrystalline diamond sublayers showed no pronounced cross-sectional variations. In summary, the experimental results provide insights into the cross-sectional evo- lution of microstructure and residual stress and the limitations of monophase multilayered diamond thin films.

KW - Cross-sectional X-ray nanodiffraction

KW - Hot-filament chemical vapour deposition

KW - Raman spectroscopy

KW - diamond multilayers

U2 - 10.1016/j.matchar.2024.113973

DO - 10.1016/j.matchar.2024.113973

M3 - Article

VL - 2024

JO - Materials characterization

JF - Materials characterization

SN - 1044-5803

IS - 212

M1 - 113973

ER -