Structure and properties of hard carbon films depending on heat treatment temperatures via polymer precursor

Phenylcarbyne polymer films were coated on silicon substrates and heat treated in 1 atm pressure of argon at various temperatures. The structural changes occurring during the heat treatment process of the polymer were investigated by Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The Raman and FTIR spectra features of the polymer showed a dependence on the heat treatment temperatures. At low temperatures (below 400 degrees C), the Raman and IR spectra of the polymer were similar to those of the original polymer. The hardness and Young's modulus of the polymer films were below 1 and 50 GPa, respectively. With increasing temperature (above 400 degrees C), thermal decomposition of the polymer occurred, resulting in structural changes of the polymer from soft amorphous hydrocarbon (400-600 degrees C) phases to hard carbon phases (above 600 degrees C). The hardness and Young's modulus increased from 1.5 and 65 GPa at 600 degrees C to 9 and 120 GPa at 1000 degrees C, respectively. It is assumed that the hard carbon film converted from the polymer might contain sp(2) and sp(3) carbon phases; high temperature of heat treatment resulted in increasing sp(2) (glassy) carbon phase in the films. (C) 1999 Elsevier Science S.A. All rights reserved.