Assessing properties of Al and Ga dopants in ZnSe

ZnSe is a material that has been studied in the past for its use in optoelectronics such as light-emitting diodes and lasers. More recently, ZnSe has become a material of interest for quantum computing applications because of its direct and wide bandgap (2.82 eV) and its ability to be grown isotopically pure. Group III elements aluminum (Al) and gallium (Ga) have a history of being donor dopants in ZnSe for optoelectronic applications, but their properties have not yet been assessed with density functional theory (DFT). This work explores the thermodynamic, electronic, and spin properties of Al and Ga defects in ZnSe with hybrid-functional DFT, and the findings are compared with experimental results from the literature. It will be shown that Al and Ga are donors that have zero spin when they occupy the Zn site in ZnSe. Al and Ga on the Se site possess interesting spin properties that could potentially be utilized for quantum applications. In particular, the +1 charge states of either Al or Ga replacing Se (AlSe1 and GaSe1) both have spin-triplet ground state configurations as well as spin-conserved intra-defect transitions well isolated from the band edges. Their properties provide interesting insight that could be helpful in furthering the search for point defects that can be utilized as spin qubits in ZnSe.