Characterization of boron carbon nitride film for humidity sensor

Boron carbon nitride films are synthesized in a horizontal quartz reactor by plasma-assisted chemical vapor deposition. Boron trichloride (BCl 3), nitrogen (N 2) and methane (CH 4) are used as source gases. Plasma of N 2 and CH 4 is produced by supplying RF power to the turn coil. BCl 3 is transported near the substrate by H 2 gas. The substrate temperature is kept at 730 °C. The BCN film with B, C, N and O composition ratios of 43%, 30%, 24% and 3% is characterized. Thermal desorption spectroscopy (TDS) measurement is carried out for the BCN film treated with D 2O. Desorption of D 2O from the BCN film occurs at 230 °C, 420 °C and 730 °C. Desorption of D 2 also occurs at 750 °C. The impedance of the as-deposited and water-treated BCN films is investigated by ac measurement. The impedance of the as-deposited BCN film depends on the − 0.9 power law of the frequency. On the other hand, the impedance of the water-treated BCN film decreases in the frequency range lower than 10 4 Hz. This is because another electrical conduction other than the quantum-mechanical tunneling hopping conduction becomes dominant due to water incorporation into the BCN film.