Influence of low positive bias on electrical properties of nitrogen doped amorphous carbon thin films by bias-assisted pyrolysis-CVD

Amorphous carbon thin films were deposited on glass substrates by using low positive bias voltage in the range of +20 V to +50 V at 500°C in 1 hour deposition. The effect of low positive bias on electrical properties of nitrogen doped amorphous carbon thin films were determined. The nitrogen doped amorphous carbon thin films were characterized by current-voltage measurement, surface profiler, UV-VIS/NIR Spectrophotometer and atomic force microscopy. Various responds of ohmic contacts were found from all samples due to different resistance value. The resistivity of amorphous carbon thin films measured from 0 V to +50 V were 4.97×10⁷ Ω·cm, 3.19×10⁷ Ω·cm, 8.33×10³ Ω·cm, 6.01×10² Ω·cm, and 1.81×10⁴ Ω·cm, respectively. The resistivity of amorphous carbon thin films were decreased as compared with undoped. Meanwhile, the values of photo response from 0 V to +50 V were 0.8003, 2.0636, 4.3841, 6.2921, and 0.9982, respectively. The electrical properties of amorphous carbon thin films were improved under low positive bias where the optimum positive voltage was found at +40 V.