CdSe Layers of Below Critical Thickness in ZnSe Matrix: Intrinsic Morphology and Defect Formation

Three main stages of the intrinsic morphology transformation of MBE grown CdSe fractional monolayers in ZnSe with increase in their nominal thickness w in the 0.1-3.0 monolayer range were found using both structural and optical characterization techniques. Emergence of the extended (15-30 nm) CdSe-enriched quantum-dot-like pseudomorphic islands at w>0.7 monolayer with the density increasing up to 2.5×10$\text{}^{10}$ cm$\text{}^{-2}$ at w=2.8 monolayer is clearly displayed in the optical properties of CdSe fractional monolayer nanostructures. The below critical thickness CdSe fractional monolayers having extremely high quantum efficiency can be very perspective as an active region of ZnSe-based blue-green lasers.