The As2V complex in silicon: Band-gap levels, migration and annealing

In this study, we used n+p mesa diodes where the highly arsenic doped n+ top layer was grown by molecular-beam epitaxy on top of a 5-μm thick p-type layer grown by chemical-vapour deposition. The diodes were irradiated with 2 MeV electrons at room temperature and the resulting defects in the p-type region were studied by Laplace and standard deep-level transient spectroscopy. A new defect with an apparent energy position of 0.20 eV above the valence band is shown to migrate from the n+ top layer into the p-type material where it is observed by DLTS. An annealing study shows that this defect grows in at ∼400 K and disappears at ∼460 K. We argue that this defect is the As2V complex, and that it is formed in the top layer when negatively charged AsV pairs, which are generated in the n+ top layer by the electron irradiation, migrate and react with the abundant and positively charged As donors. Once formed, the As2V complex diffuses into the p-type material.