1 research outputs found
Chemical Vapor Deposition of Graphene on Self-Limited SiC Interfacial Layers Formed on Silicon Substrates for Heterojunction Devices
Direct
chemical vapor deposition (CVD) of graphene on any desired
substrate is always required to manufacture high-quality heterojunctions
with excellent interfacial properties. Herein, the growth of graphene
on cubic-silicon carbide (3C-SiC) surfaces using conventional high-temperature
direct thermal CVD and plasma-enhanced CVD (PECVD) is explored, which
is hardly reported to date. Since 3C-SiC substrates are not available,
the controlled self-limited 3C-SiC layers on the Si(100) substrates
were grown at different temperatures (900–1200 °C) via
thermal-CVD technique to obtain virtual 3C-SiC substrates. The direct
production of graphene via thermal CVD could not be achieved on such
3C-SiC surfaces. The density functional theory and molecular dynamics
simulations confirm that the carbon atom diffusion over the 3C-SiC
surface is extremely low, like over the Si surface, which leads to
no graphene growth. A similar growth mechanism may be attributed to
their similar crystal structure viz diamond cubic for Si and zinc
blend for 3C-SiC. However, graphene nanowalls (GNWs) were successfully
grown on both Si and 3C-SiC/Si surfaces at 700 °C via the PECVD
technique, where similar surface morphologies were observed because
the growth mechanism of GNWs is independent of substrate type. Moreover, I–V characterization was performed
for different SiC/Si heterostructures and their corresponding GNWs/SiC/Si
heterostructures, respectively. The current conduction improved considerably
more for GNW/SiC/Si heterostructures as compared to SiC/Si heterostructures,
but the creation of a SiC interfacial layer as well as its quality
affected the conductivity of GNWs/SiC/Si heterostructures. The inevitable
formation of an interfacial SiC layer during the direct graphene growth
via thermal CVD on Si substrates can seriously affect the performance
of graphene/Si heterojunction devices. Hence, PECVD growth of graphene
is an ideal option to fabricate graphene/Si heterojunction devices
with excellent interfacial properties or graphene/3C-SiC/Si heterojunction
devices for various electronic/optoelectronic applications such as
gas sensors and photovoltaic devices