Defect compensation in the p-type transparent oxide Ba2BiTaO6

Abstract

Ba₂BiTaO₆ is a transparent p-type oxide recently discovered and exhibiting attractive hole mobility but low carrier concentration. Using first-principles computations, we study how defects influence the carrier concentration in Ba₂BiTaO₆. The calculated defect formation energies confirm that K is an adequate p-type shallow extrinsic dopant but that high p-type doping is prevented by the presence of compensating, “hole-killing”, intrinsic defects: O vacancies but also Ta on Bi anti-sites. Our work stresses the inherent difficulty in doping Ba₂BiTaO₆ to high carrier concentration and discusses a few avenues towards this goal.