Wednesday, September 30, 2015

The fundamentals of CVD of boron-carbon thin films


Here is a great publication on the fundamentals of CVD of boron-carbon thin films from Henrik Pedersen and co-wokers at Linköping University, Sweden and Philipps-Universität Marburg. Such freedom they have, with respect to temperature... but then again it is rather cold in Sweden.

Gas phase chemical vapor deposition chemistry of triethylboron probed by boron–carbon thin film deposition and quantum chemical calculations

Mewlude Imam, Konstantin Gaul, Andreas Stegmüller, Carina Höglund, Jens Jensen, Lars Hultman, Jens Birch, Ralf Tonner and Henrik Pedersen

J. Mater. Chem. C, 2015, Advance Article
DOI: 10.1039/C5TC02293B

We present triethylboron (TEB) as a single-source precursor for chemical vapor deposition (CVD) of BxC thin films and study its gas phase chemistry under CVD conditions by quantum chemical calculations. A comprehensive thermochemical catalogue for the species of the gas phase chemistry of TEB is examined and found to be dominated by β-hydride eliminations of C2H4 to yield BH3. A complementary bimolecular reaction path based on H2 assisted C2H6 elimination to BH3 is also significant at lower temperatures in the presence of hydrogen. Furthermore, we find a temperature window of 600–1000 °C for the deposition of X-ray amorphous BxC films with 2.5 ≤ x ≤ 4.5 from TEB. Films grown at temperatures below 600 °C contain high amounts of H, while temperatures above 1000 °C result in C-rich films. The film density and hardness are determined to be in the range of 2.40–2.65 g cm−3 and 29–39 GPa, respectively, within the determined temperature window.