Defect-engineering in SiC by ion implantation and electron irradiation

Three examples are given, which show that ion implantation and electron irradiation can drastically modify the electrical properties of SiC and SiC-based MOS capacitors. (1) It is demonstrated that sulphur ions (S+) implanted into 6H-SiC act as double donors with ground states ranging from 310 to 635 meV below the conduction bandedge. (2) Co-implantation of nitrogen (N+) – and silicon (Si+) – ions into 4H-SiC leads to a strong deactivation of N donors. Additional experiments with electron (e−)-irradiated 4H-SiC samples (E(e−) = 200 keV) support the idea that this deactivation is due to the formation of an electrically neutral (Nx–VC, y)-complex. (3) Implantation of a surface-near Gaussian profile into n-type 4H-SiC followed by a standard oxidation process leads to a strong reduction of the density of interface traps Dit close to the conduction bandedge in n-type 4H-SiC/SiO2 MOS capacitors.