Induced defect levels of P and Al vacancy-complexes in 4H-SiC: A hybrid functional study

The electronic behaviour of high-dose phosphorus implanted in 4H-SiC is mainly desirable to obtained lower sheet resistance of 4H-SiC. Al doping on the other hand acts as an acceptor, improves the dielectric properties of 4H-SiC and has very low diffusivity in SiC. Using a hybrid density functional theory, we investigated the properties of Al and P defect-complexes in 4H-SiC a wide band-gap semiconductor that is promising for applications in high-frequency and high-temperature electronic device. We show that vacancy-complexes formed by PSi and AlSi are more energetically stable than those formed by PC and AlC. The defects with silicon vacancy are predicted to experience more lattice distortion compared to those formed with carbon vacancy. While vacancy-complexes formed with PSi or PC and VC induced double donor levels, vacancy-complex formed with substitution of P and VSi induced negative-U charge state ordering. The Al with VC related vacancy-complexes induced deep single donor and acceptor levels, and Al with VSi induced only acceptor and negative-U ordering.