Speaker
Description
Summary
We have used DFT from first-principles to predict the properties of various P and Al related vacancy-complexes in 4H-SiC: reporting their formation energies, binding energies, charge state transition levels and negative-U charge state ordering properties. The vacancy-complexes with silicon vacancy were predicted to experience more lattice distortion compared to those formed with carbon vacancy. The P and Al related vacancy-complexes showed that they are stable with respect to their binding energies under equilibrium conditions. While the vacancy-complexes formed by the P Si and Al Si are more energetically stable, the vacancy-complexes formed by PC and AlC had high formation energies. The PSiVC and AlSi VC are energetically most favourable defects at any Fermi-level in the band gap of 4H-SiC for P and Al related vacancy-complexes, respectively. This result also corroborate earlier report on the characterization of this defect. The defect levels induced by the P related vacancy-complexes are very shallow close to the conduction band minimum for the single and double acceptor levels, and deep for both the single and double donor levels. Furthermore, only the PSi VSi and PC VSi induced negative-U charge state ordering that are lying deep in the band gap of 4H-SiC. While the Al with VC related vacancy-complexes on the other hand induced deep single donor and acceptor levels, the Al with VSi induced only acceptor and negative-U charge state ordering. These results provide an insight for future work which is crucial for improving the quality of n-type SiC.