Cathodoluminescence study of quantum-size and alloying effects in single fractional monolayer CdSe/ZnSe structures

Luminescence properties of single fractional monolayer CdSe/ZnSe structures with nominal, thickness of 1.25 to 3.6 monolayers have been investigated b y means of cathodoluminescence (CL) spectroscopy. The CL spectra exhibit sh arp peaks superimposed on a broad luminescence band due to individual CdSe- enriched dots spontaneously formed in the CdSe layer. By fitting the CL spe ctra to the transition energies calculated by a quantum disk model taking i nto account compositional alloying and dot sizes, we have determined Cd con centrations in CdSe-enriched dots. The results are in good agreement with s tructural data, and indicate that the blue shift of the dot luminescence wi th decreasing nominal thickness is due to the alloying effect.