Atomistic Simulations of CdS Morphologies

Atomistic simulations based on the static lattice model are performed to calculate the equilibrium and growth morphologies of CdS polymorphs. Morphologically important surfaces are optimized to calculate their structural and energetical properties such as surface and attachment energies. A common feature of all the nonpolar CdS surfaces is the outward movement of their anions and the inward movement of their cations. The relaxation of surfaces is critically important as it changes the surface and attachment energies significantly. The {112̅0} surface has the lowest surface energy (0.58 J/m²) for the wurtzite phase of CdS, whereas {110} surface has the lowest surface energy (0.62 J/m²) for the zincblend phase of CdS. The {101̅0}, {123̅0}, and {11̅00} surfaces of wurtzite CdS all have the same surface energy value (0.60 J/m²), which is very close to that of {112̅0} surface. Therefore, all these surfaces appear in the equilibrium morphology of the wurtzite CdS. The equilibrium morphology of the zincblend CdS is completely dominated by the {110} surface. The growth morphology of the wurtzite CdS consists of {101̅0}, {11̅00}, {0001}, and {0001̅} surfaces. The growth morphology of the zincblend CdS is found to be identical to its equilibrium morphology and, therefore, includes only the {110} surface