Effects of Radical Species on Structural and Electronic Properties of Amorphous Carbon Films Deposited by Radical-Injection Plasma-Enhanced Chemical Vapor Deposition

Abstract

Amorphous carbon (a-C) films are deposited using a radical-injection plasma-enhanced chemical vapor deposition (RI-PECVD) system employing a mixture of H 2 and CH 4 gases. Variations in the structural and electronic properties of the resulting films with changes in the residence times of radical species and molecules are investigated by varying the total gas flow rate from 50 to 400 sccm. With decreasing residence time, the deposition rate is found to gradually increase, reaching a maximum value at a residence time of 6 ms, after which a decrease was observed. Optical emission spectra showed that the relative intensity of the CH emission increased with decreasing residence time. These results indicate a change in the dominant radical species resulting from suppression of the dissociation of radicals and molecules. Increasing amorphization and an obvious increase in the Tauc gap from 0.6 to 0.9 eV are found with decreasing residence time, while there is little change in the hydrogen content of the films. From these data, it is evident that control over the structural properties and optical bandgap of a-C films can be realized by optimizing the distribution of radical species.

Plasma enhanced synthesis of N doped vertically aligned carbon nanofibers on 3D graphene

“…The deposition of CNFs on 3DG led to an increase in D peak intensity around 1350 cm −1 which represents disorder in the previous graphene structure. Another reason for high D peak could be attributed to the fact that the deposition of VACNF was done using PECVD, which generally creates a lot of radicals that affect the quality of carbon structure produced . The first‐order G band around 1580 cm −1 , which is indicative of planar sp 2 vibrations, was seen after deposition of VACNF as well.…”

Effects of Ion Bombardment Energy Flux on Chemical Compositions and Structures of Hydrogenated Amorphous Carbon Films Grown by a Radical-Injection Plasma-Enhanced Chemical Vapor Deposition

“…The growth of a-C:H films was performed using a radical-injection plasma enhanced chemical vapor deposition (RI-PECVD) system, in which two plasma sources were stacked and connected through a showerhead electrode [20,21]. Figure 1 shows the schematic diagram of RI-PECVD system.…”

Chemical Vapour Deposition of Graphene—Synthesis, Characterisation, and Applications: A Review

“…In fact, formation of graphene layers on Ni dates back to more than 50 years where it was observed in industrial applications [21,134,135]. Ni (111) has the least lattice mismatch with graphene compared to other transition metals (< 1%) making it catalytically more favourable for growing graphene [136]. Graphene grows on Ni through bulk diffusion [21,115,118,136].…”

“…Mogera et al investigated twisted multilayer graphene growth on polycrystalline Ni [136]. It was found that graphene growth on polycrystalline Ni enhances Ni (111) orientation when compared with other treatments of Ni including annealing. Figure 18 shows the difference between the interlock of the sample with and without a graphene layer.…”

“…CCP takes advantages over ICP for the lower ionisation rate of the later making most of the gases species neutrals, rather than radicals like the case of ICP. However, the voltage-drop between the glow discharge and substrate in CCP promotes ion bombardment to the grown film resulting in a formation of amorphous layer [ 110 , 111 ]. Yen et al successfully prepared a single layer of graphene film of full-coverage over the substrate in less than 30 s using the CCP system [ 112 ].…”