It is proven that introduction of graphene into typical
heterostructures
can effectively reduce the high interfacial thermal resistance in
semiconductor chips. The crystallinity of graphene varies greatly;
thus, we have investigated the effects of single-crystal and polycrystalline
graphene on the thermal transport of AlN/graphene/3C-SiC heterostructures
by molecular dynamics. The results show that polycrystalline graphene
contributes more to the interfacial thermal conductance (ITC) inside
the chip with a maximum increase of 75.09%, which is further confirmed
by the energy transport and thermal relaxation time. Multiple analyses
indicate that grain boundaries lead to the increase in C–Si
covalent bonds, and thus, strong interactions improve the ITC. However,
covalent bonding further causes local tensile strain and wrinkles
in graphene. The former decreases the ITC, and the latter leads to
the fluctuation of the van der Waals interaction at the interface.
The combined effect of various influential factors results in the
increase in the ITC, which are confirmed by phonon transmission with
0–18 THz. In addition, wrinkles and covalent bonding lead to
increased stress concentration in polycrystalline graphene. This leads
to a maximum reduction of 19.23% in the in-plane thermal conductivity,
which is not conducive to the lateral diffusion of hot spots within
the chip. The research results would provide important guidance in
designing for high thermal transport performance high-power chips.