Abstract
By means of first-principles calculations, we have investigated the effects of various Li-doping on the exchange interaction and the formation energy in bulk GaN with Ga vacancies. Although the Ga vacancies can induce ferromagnetism in GaN, their formation energy is rather high. Our calculations show that Li-doping can effectively tune the formation energy of Ga vacancies. It is revealed that the stabilizing effect depends on whether the number of holes is increased or decreased after Li-doping. When Li atoms substitutes for N atoms or occupies the interstitial sites, the holes are reduced and the formation energy of Ga vacancies is lowered. In contrast, Li substituting for Ga generates additional holes in the system, leading to an enhancement of the formation energy of Ga vacancies and making the system less stable.
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