Growth Mechanism of Graphene Synthesized on Ni/Cu Alloy through CVD Method and Use Graphene as a Diffusion Barrier for Thermoelectric Device
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Graphene is the first two-dimensional (2D) atomic crystal available to the world. It is a two-dimensional sheet of sp2 -hybridized carbon. Its extended honeycomb network is the basic building block of other important allotropes; it can be wrapped to form 0 dimension fullerenes, rolled to form 1dimension nanotubes and stacked to form 3 dimension graphite. Long-range π-conjugation in Graphene yields extraordinary thermal, mechanical, and electrical properties, which have long been the interest for many theoretical studies and more recently became an exciting area for experimentalists. Large single crystal Graphene is preferred for applications such as electronic devices and diffusion barriers. Also to deliver unique performance, single crystal Graphene is desired. Here we studied the growth mechanism behind the world’s first inch size single crystal Graphene with a fast growth rate on Ni/Cu alloy substrate through chemical vapor deposition method. Our observation indicated that body participation and surface adsorption both contributed to the fast growth of Graphene on Ni/Cu alloy and the present of Ni element suppressed nucleation of Graphene seed much more efficiently than methods reported by other groups. We further researched the effect of Ni content on graphene growth rate and nucleation density. We also used Graphene as diffusion barrier to prevent Ni metal solder diffusing into PbTe thermoelectric material at high operation temperature (500C). Our preliminary results showed single layer Graphene is a promised high temperature diffusion barrier for thermoelectric device. Only less than 10% of Ni was found diffused into PbTe while device without Graphene has nearly 40% of Ni in PbTe. InTe/mG/PbTe (multilayer graphene barrier) device showed a ~40% more power output than InTe/PbTe device. We propose that multilayer Graphene transferred on PbTe device would prevent metal diffusing into PbTe and improve the power output of PbTe devices.