The role of pinhole structures in Mo thin films on multi-layer graphene synthesis

Abstract

In this study, the density and oxygen content of Mo thin films were varied by changing the deposition conditions, in order to understand their influence on the catalytic activity of Mo 2 C for the synthesis of multi-layer graphene (MLG). Structural and morphological analysis of Mo 2 C in relation to its catalytic activity indicate that the density of Mo plays a more critical role on MLG synthesis than the oxygen content. Results show that the pinholes present in relatively low density Mo layers act as catalytically active defect sites, promoting MLG synthesis. OPEN ACCESS RECEIVED

Bifunctional catalytic effect of Mo2C/oxide interface on multi-layer graphene growth

“…In our earlier work 13 , it is shown that the nucleation and growth (or absence thereof) of MLG on Mo 2 C was strongly related to the presence (or absence) of pinholes in Mo 2 C. From this observation, we hypothesize that the Mo 2 C/SiO 2 interface can play an important, bifunctional, role by catalyzing different reactions for MLG growth. To test our hypothesis, in this section we investigate the role of the Mo 2 C/SiO 2 interface in MLG growth on pinhole-free Mo 2 C.…”

“…In the first part, the thin film deposition process flow of Mo catalysts on Si/SiO 2 substrates will be given. This process is known to result in pinhole-free Mo 2 C, which does not yield MLG growth upon subsequent CVD processing 13 . In the second part, the deposition/patterning of oxides will be explained in order to create an interface which is expected to play a role in MLG synthesis.…”

“…After fabrication of samples with exposed Mo/oxide interfaces, a CVD process is applied to all samples using a cold wall reactor system in presence of CH 4 , Ar and, H 2 gasses at 1000 °C for 35 min, using the same parameters from our previous study 13 . To test the role of hydrogen in the MLG growth process, additional experiments were done where the same CVD process was applied, but without H 2 .…”

“…In our previous work, the growth of multi-layer graphene (MLG) was linked to the presence of pinholes in Mo 2 C thin films 13 . Such pinholes could expose the underlying oxide, which may play an important role in the graphene synthesis process.…”