Atomic force microscopy (AFM) and photoluminescence (PL) measurements were carried out to investigate the formation and the optical properties of CdTe∕ZnTe nanostructures with various CdTe thicknesses grown on Si (100) substrates by using molecular beam epitaxy and atomic layer epitaxy. AFM images showed that uniform CdTe∕ZnTe quantum dots with a CdTe layer thickness of 2.5 ML (monolayer) were formed on Si (100) substrates. The excitonic peaks corresponding to transitions from the ground electronic subband to the ground heavy-hole band in the CdTe∕ZnTe nanostructures shifted to a lower energy with increasing thickness of the CdTe layer. The activation energies of the carriers confined in the CdTe∕ZnTe nanostructures grown on Si (100) substrates were obtained from the temperature-dependent PL spectra. The present observations can help improve understanding of the formation and the optical properties in CdTe∕ZnTe nanostructures with different CdTe thicknesses grown on Si (100) substrates.