Low Density of Interface States in n-type 4H-SiC MOS Capacitors Achieved by Nitrogen Implantation

摘要

A surface-near Gaussian nitrogen (N) profile is implanted into n-type 4H-SiC epilayers prior to a standard oxidation process. Depending on the depth of the oxidized layer and on the implanted N concentration, the density of interface states D_(IT) determined in corresponding 4H-SiC MOS capacitors decreases to a minimum value of approx. 10~(10) cm~(-2)eV~(-1) in the investigated energy range (E_C-(0.1 eV to 0.6 eV)), while the flat-band voltage increases to negative values due to generated fixed positive charges. A thin surface-near layer, which is highly N-doped during the chemical vapour deposition growth, leads to a reduction of D_(IT) only close to the conduction band edge.