Ab initio studies of arsenic and boron related defects in silicon mesa diodes

摘要

E centers are known to diffuse around 400 K in Si and may then form larger donor-vacancy defects such as As_2V in heavily doped n-type Si doped with As or AsBV if they diffuse into p-type regions. Ab initio methods are used to explore these possibilities. The AsV defect possesses electrical levels in agreement with experiments. The AsBV defect is found to exhibit a charge-dependent structure, has a barrier to dissociation of ～1.4 eV, and possesses an acceptor level at 0.27 or 0.47 eV above the valence band top depending on the defect structure. The As_2V defect possesses only an acceptor level at 0.22 eV below the conduction band. Comparison is made with recent experiments carried out on mesa diodes.