Realizing the large current field emission characteristics of single vertical few-layer graphene by constructing a lateral graphite heat dissipation interface.

ABSTRACT

With the potential to be an excellent field electron emitter, few-layer graphene (FLG) has to avoid Joule heat induced vacuum breakdown during high current field electron emission. Creating a good heat dissipation path is the key factor maintaining the heat equilibrium of a field emitter. In this work, a graphite interlayer was grown between the FLG and the tungsten substrate. The graphite interlayer with its good in plane electrical and thermal conductivities helps FLG dissipate the heat in the lateral direction efficiently and broaden the heat dissipation path. As a result, both the temperature of the FLG and the chance of vacuum breakdown were reduced. The destructive in situ TEM field emission test of a single FLG showed that the breakage of the graphite interlayer during field emission blocks up the lateral heat dissipation path, causes heat accumulation and finally induces the vacuum breakdown of FLG. Benefiting from the graphite interlayer, the high current field emission characteristics of a single FLG were achieved. The maximum field emission current of six single FLG samples was between 78 and 233 µA with the corresponding current densities in the range of 1.2 × 107-5.85 × 108 A cm-2. This finding demonstrates that interface heat engineering is crucial for nanomaterial-based field emitters that work under high current and high temperature conditions.