Structural, nanomechanical, field emission and ammonia gas sensing properties of nitrogenated amorphous carbon films deposited by filtered anodic jet carbon arc technique

This paper reports the effect of substrate bias on the structural, nanomechanical, field emission and ammonia gas sensing properties of nitrogenated amorphous carbon films embedded with nanocrystallites (a-C: N: nc) deposited by a filtered anodic jet carbon arc (FAJCA) technique. The films are characterized by X-ray diffraction, high resolution transmission electron microscopy, energy dispersive X-ray spectroscopic analysis, Raman spectroscopy, nanoindentation, field emission and ammonia gas sensing measurements. The properties of the films obtained are found to depend on the substrate bias. The maximum hardness (H)=42.7 GPa, elastic modulus (E)=330.4 GPa, plastic index parameter (H/E)=0.129 and elastic recovery (% ER)=74.4% have been obtained in a-C: N: nc films deposited at −60 V substrate bias which show the lowest ID/IG=0.43, emission threshold (ET)=4.9 V/µm accompanied with the largest emission current density (Jmax)=1 mA/cm2 and field enhancement factor (β)=1805.6. The gas sensing behavior of the a-C: N: nc film has been tested by measuring the change in electrical resistance of the sample in ammonia environment at room temperature with the fast response and recovery time as 29 and 66.9 s, respectively.