Temperature dependency of the LPCVD growth of ZrC with the ZrCl4–CH4–H2 system

The ZrC films were grown on graphite substrates by a low pressure chemical vapor growth (LPCVD) process using zirconium tetrachloride (ZrCl4) and methane (CH4) as a source gas, and hydrogen (H2) as a dilution gas. The experiments were carried out with various growth temperatures ranging from 1523 to 1773 K to investigate the effect of the temperature on the growth of the ZrC films. The stoichiometric ZrC film grew at 1623 and 1673 K. The growth rate of the ZrC films increased with an increasing growth temperature. The conversion temperature for the growth mechanism from a surface reaction to a mass transport reaction existed in the growth temperature range of 1623 and 1673 K. As the growth temperature increased, the preferred orientation of the ZrC films changed from (111) to (220) to (200) in turn. Rectangular grains with column and small hexagonal shaped ZrC grains, which were grown at a low growth temperature, changed into large faceted grains at a high growth temperature. The surface morphology changes of the ZrC films were caused by a change of the preferred orientation of the ZrC film with increasing growth temperatures.