Influence of negative dc bias voltage on structural transformation of carbon nitride at 600 °C

Carbon nitride (CN) thin films were prepared at 600 degrees C by rf plasma pulsed laser deposition. As we increased the magnitude of the negative de bias voltage, the CN bonds were transformed from a mixture of sp(2) C-N and sp(3) C-N states into a CN phase predominated by tetrahedral CN bonds. A biasing threshold of this transformation occurred due to the annihilation of the graphite microstructure, which coincided with a threshold of significant nitrogen incorporation. We found that suppression of graphite supersaturation appeared to be important for the formation of the tetrahedral sp(3) C-N bonds. The nitrogen content of these films is stable upon annealing at 800 degrees C in vacuum. (C) 1998 American Institute of Physics.