B is more likely to form than V 0 B when AB is p-type. The opposite is true when E F is closer to the conduction band minimum, where the formation energy of V 0 B is lower than that of V +2 B . For illustrative purposes, we show that the formation energies of V +2 B and V 0 B cross at E F = E (+2/0) , signifying a transition in the charge state of V B . A chemical interpretation consistent with this charge state transition is that a molecular orbital, which is induced by the defect, exists with energy E (+2/0) above the valence band maximum. The molecular orbital is unfilled when E F is below in energy (forming the V +2 B charged defect) and filled when E F is above in energy (creating the V 0 B defect), as shown in Figure . Note that this charge transition need not occur in the band gap, as the molecular orbital(s) induced by the defect may appear inside the bands instead.