Structural and optical properties of CdSe/ZnSe self-organized quantum dots

We have observed a single CdSe quantum dot (QD) by high-resolution plan-vie w transmission electron microscopy images to investigate the shape and size of CdSe QDs naturally formed on ZnSe(0 0 1) surfaces. A tentative model is that the base structure of a CdSe dot is rhombic with the long axis of abo ut 20 nm in length along the [1 (1) over bar 0] direction. The lattice spac ing inside the CdSe dot is completely the same as that outside the CdSe dot . The polarization dependence of photoluminescence (PL) from CdSe QDs is ta ken to investigate the effect of the QD shape on the optical property. The PL spectra are strongly polarized parallel to the [1 (1) over bar 0] direct ion, which is consistent with the proposed model of CdSe QDs. The CdSe cove rage dependence of polarization PL spectra indicates that the PL polarizati on degree increases with QD formation. (C) 2001 Elsevier Science B.V. All r ights reserved.