Atomic bonds in boron carbon nitride films synthesized by remote plasma-assisted chemical vapor deposition

Boron carbon nitride (BCN) films are synthesized by remote plasma-assisted chemical vapor deposition (RPCVD) method. The present experimental apparatus is featured by introducing BCl3 gas near the substrate without mixing to plasma consisting of N2 and CH4 gases. Two sample groups of the BCN films are prepared. One is grown with various CH4 flow rates, and another is grown with various BCl3 flow rates. The composition ratio of the constituent atoms, atomic bonds and optical bandgap are investigated. C composition ratio of the BCN film increases with increasing CH4 flow rate, leading to a reduction in the optical bandgap with increasing C composition ratio. On the other hand, it is found that no significant variation in the composition ratio occurs for the BCN films grown with various BCl3 flow rates and that the optical bandgap decreases with increasing BCl3 flow rate. This behavior of the optical bandgap is related to a change of the atomic bonds in the BCN film grown with various BCl3 flow rates.