Stress distribution in thin heteroepitaxial diamond films on Ir/SrTiO3 studied by x-ray diffraction, Raman spectroscopy, and finite element simulations

Abstract

The residual stress in thin diamond films with a strongly improved heteroepitaxial alignment has been studied by x-ray diffraction and micro-Raman spectroscopy. The measurements have been compared with the predictions from finite element simulations. The diamond films have been deposited by microwave plasma chemical vapor deposition at a temperature of 700°C on thin (200 nm) iridium buffer layers on SrTiO3(001). Three different regions have been found for a 600 nm thick diamond film: (I) a high quality epitaxial central area with >109 cm−2 oriented diamond grains showing a mosaic spread of only ≈1°; (II) a ringlike area of isolated epitaxial islands; and (III) a nontextured closed film at the edge of the sample. In area I the stress tensor was determined from the mean shift of the x-ray Bragg reflections. It can be interpreted in terms of a plane, biaxial stress state with σ=−4.9 GPa which is confirmed by micro-Raman measurements. Analyzing the diamond (004) and (311) peak profiles measured by x-ray diffraction (XRD) using monochromatic CuKα1 radiation allows us to distinguish a strongly shifted main component and a weaker, broader component with a minor shift. Finite element simulations predict a pronounced elastic relaxation of the thermal stress at rugged surfaces thus explaining this minor component. They also substantiate a stress reduction by more than 80% as observed by Raman measurements in area II. Combining all measurements taken in the different areas with the predictions of the simulation allows to separate four contributions, i.e., the thermal stress, elastic stress relaxation at a rugged surface, inhomogeneous stress contributions from the coalescence of the grains, and finally coherence stress due to lattice misfit.

Site selective growth of heteroepitaxial diamond nanoislands containing single SiV centers

“…The major contribution stems from the micro stress of typically several GPa that can be derived from the line broadening (width of about 15 cm −1 ) in Raman measurements of thin heteroepitaxial diamond layers. 22 Its formation is characteristic for the merging of the individual grains during the early stage of film growth. However, elastic relaxation can reduce strain for nanostructures.…”

Analysis of residual stress in diamond films by x-ray diffraction and micro-Raman spectroscopy

“…Measurements on both natural diamond 23 and SHOCK DIAM, 24 which consist of diamond crystallites with different grain sizes, lead to a linear shift of 2.9 cm Ϫ1 /GPa. Values even three times smaller 25 can be found in the literature. We use the value of SHOCK DIAM ͓27͔ because of its similarity in the form to the CVD grown diamond films.…”

Mosaicity, dislocations and strain in heteroepitaxial diamond grown on iridium

“…3(b)). The full width at half maximum (FWHM) of this curve, quantifying the mosaicity, is about 0.6°, in the same order of magnitude than other works on heteroepitaxial diamond for comparable thicknesses [14,15]. A large ϕ-scan (azimuthal scan) was acquired on the asymmetric 〈202〉 reflections (Fig.…”