Theoretical study of cubic versus tetragonal structures of defect zinc-blende semiconductors:CdIn2Se4

The structural properties of ${\mathrm{CdIn}}_2$ ${\mathrm{Se}}_4$ are calculated from first principles with use of the local-density approximation and norm-conserving pseudopotentials. Particular attention has been paid to the relative stability of the tetragonal and cubic spinel phases. We find that (i) the tetragonal phase is the most stable at zero pressure, (ii) this phase actually is a pseudocubic one (c/a=1), (iii) the combined effect of the lower symmetry and of the presence of defects induces distortions in the anion sublattice, and (iv) a transition to the spinel phase occurs under an applied pressure of ∼10 kbar. The electronic properties of the two phases are also discussed in terms of the electron charge-density distribution and density of states.