Effect of electric field on formation energies of point defects around metal/SiC and metal/GaN interfaces: first-principles study

Formation energies of point defects, such as anion vacancies and substitutional dopants, around metal/(SiC, GaN) interfaces in electric fields are studied by the first-principles calculation. It is shown that when the positive voltage is applied to the metal layers, with increasing the electric field, the formation energy decreases for the anion vacancies and donor-type dopants, while it increases for acceptor-type dopants. We show that such variation of formation energy is caused by the electron transfer between electronic states of defects and metal electrode and the associated variation of ionization charge of defects. The present results will help to control the generation of point defects using the electric field.