| Popis: |
This chapter will study emission processes in an Mn-doped quantum dot. Theoretical models for magnetophotoluminescence of an Mn2+-doped semiconductor core-shell colloidal quantum dot will be considered to explain the experiment results from a recent magnetophotoluminescence study of a strongly confined diluted magnetic semiconductor (DMS) in Mn2+-doped ZnSe/CdSe core-shell colloidal nanocrystals. The yellow emission characterized for Mn2+ that is associated with the d−d internal transition 4T1−6A1 was reported as not suppressed in an applied B//z magnetic field and unpolarized as usual and instead, an Mn photoluminescence (PL) circular polarization has been observed. The Mn2+ PL has been found to have a large split between σ+ and σ− components that depends on the applied field. This behavior, which has not been found in characteristics of the Mn2+ PL in bulks and other conventional DMS materials, is the result of the strong confinement of the nanocrystal and its properties. Our theory and calculations show that the reasons the yellow Mn2+ PL band in quantum dots is not suppressed under an applied magnetic field originates from the existence of the internal piezoelectric dipole moment as well as the Coulomb and exchange interaction of the impurity ions with the confined electrons inside the dots. |
