Interfacial treatment of 4H SiC/SiO₂ interface by shallow boron ion implantation

Shallow boron ion implantation at the 4H SiC/SiO₂ interface was performed using boron multicharged ions from laser plasma. A Q-switched Nd:YAG laser (wavelength 1064 nm, pulse width 7 ns, and fluence 135 J/cm²) was used to ablate a boron target generating a dense plasma source of multicharged ions. Ions up to B⁵⁺ are generated. The ions are deflected by an electrostatic field to separate them from the neutrals. SRIM simulation was used to estimate the ion penetration depth in the SiC substrate. The optical bandgap of the 4H SiC was reduced by boron ion implantation. Several MOSCAP devices were fabricated. High-low C-V measurements were used to characterize the MOSCAPs. Shallow boron implantation in the SiC/SiO₂ interface reduces the flatband voltage from 4.5 V to 0.04 V.