Characterization of amorphous carbon nitride by bottom-gated thin-film structure

Abstract We describe the characterization of nitrogen-incorporated amorphous carbon (a-C:N) films by using a double beam method. The carrier transport of a-C:N films deposited at various substrate temperatures was investigated using a bottom-gated thin-film transistor (TFT). At substrate temperatures below 300 °C, the optical band gap (Eopt) and the Raman intensity ratio between the D (∼1360 cm− 1) and G (∼1590 cm− 1) peaks (ID / IG) of an a-C:N film deposited at room temperature were observed to vary only marginally from 1.9 eV and 0.88, respectively. The electrical conductivity of the a-C:N film increased by more than four orders of magnitude with an increase in the substrate temperature from 150 to 300 °C due to an improvement in the activation of the nitrogen-incorporated a-C film caused by the thermal annealing effect. Based on the Eopt and ID / IG values, we concluded that this behavior is not responsible for the change in the hybridization of carbon atoms. The a-C:N based TFT exhibited an ambipolar transport with the strong p-type operation. The field effect hole mobility (μh) attained a value as high as 1.7 × 10− 4 cm2/Vs. In this study, one of the important results is that μh increased with the substrate temperature due to the increase in film conductivity. We found that the highest success yield of transistor operation of 38% was obtained from the a-C:N TFTs deposited at a substrate temperature of 290 °C.