Electrical behaviour of metal/a-C/Si and metal/CN/Si devices Original Research Article

Electrical characterisation of metal/carbon/Si devices was performed. Amorphous carbon films rich in sp3 bonds were grown onto n-type Si substrates by RF magnetron sputtering at room temperature. Different deposition conditions were used to create different sp3 and sp2 configurations in order to examine their influence on the performance of electronic devices. Suitable metalisation was used to fabricate devices, which were then characterised electrically. Electrical characterisation using I–V, C–G–V and G–ω techniques showed temperature dependent currents through the devices which increase rapidly when forward bias is applied. This behaviour was found to be dependent on the sp3–sp2 contents of the films. The devices behaved like metal–insulator–semiconductor diodes with a defect insulator resulting in creating thermally activated currents through the devices. The effect of nitrogen introduced in the growth process to produce carbon nitride films was also examined. Different amounts of nitrogen were used and the same characterisation process has been used for a variety of samples. The films were nearly perfect insulators and the corresponding devices showed a clear MIS behaviour. Thus, the room temperature magnetron sputtering technique produced films, with electronic properties dependent on the C–C bonding configuration. Moreover it is shown that the nitrogenated films made under certain conditions can be used as insulators in devices.