DX centers in GaAs and GaSb -: art. no. 075210

We propose a DX center, beta-cation-cation-bonded (CCB)-DX, in III-V semiconductors based on first-principles calculations. Detailed structural and energetic analyses show that the relative stability of the beta-CCB-DX center with respect to two other previously proposed ones strongly depends on the size of the dopant atom. We find that the beta-CCB-DX center is most stable when a small group-VI atom replaces the host anion in III-V semiconductors. With the discovery of this DX center, several DX-related phenomena can be explained consistently.