Enhanced growth of β-C3N4 crystallites at a high substrate temperature

The growth of beta-C3N4 crystallites is studied at various substrate temperatures by an inductively-coupled plasma sputtering method using 500 W of radio frequency power to enhance the gas dissociation. The crystallites deposited are demonstrated to be beta-C3N4 phase rather than other phases from the transmission electron diffraction and the X-ray photoelectron spectroscopy results. Upon increasing the substrate temperature from 400 degrees C to 800 degrees C, beta-C3N4 crystallite size increases from 0.02 mu m to 0.2 mu m, but the [N]/[C] atomic ratio in the film decreases slightly from 1.0 to 0.85, suggesting that the film contains larger beta-C3N4 crystallites in a less nitrogenated amorphous carbon matrix at a higher temperature, The film deposited at 800 degrees C exhibits a highly spotty transmission electron diffraction pattern and contains a high percentage (90%) of sp(3) C-N bonding as estimated from X-ray photoelectron spectroscopy. The results suggest that a high substrate temperature enhances the formation of beta-C3N4 crystallites at a high degree of gas dissociation.