Magnetooptic properties of semiconductor quantum dots in glass composites

Low dimensional systems of semiconductor quantum dots in glass composites exhibit interesting physical properties arising from spatial confinement effects; an example is the discretization of the energy spectrum. In semiconductor quantum dots, electronic wave functions experience effects of quantum confinement arising from the dot-glass interface acting as an infinite potential barrier, effectively creating an infinite potential well. This leads to electronic transitions having higher energies with decreasing dot size. The shift of the electronic energies is associated with an increase in the Faraday rotation. Magnetooptic measurements are quasi-elastic light scattering for type II–VI semiconductor quantum dots in a borosilicate glass matrix have been studied. The Faraday rotation of the quantum dot glass composite shows an increase over the bulk semiconductor crystal and the pure borosilicate glass. The Verdet constant, initially constant, demonstrates an increase to another, higher constant value, at higher magnetic fields. This kink in the slope is achieved at lower fields with smaller quantum dots, and this finding is noted to be invariant, throughout the various samples studied. This finding is felt to be likely associated with alteration of electronic energy levels, associated with quantum confinement, and may be due, specifically, to excitonic confinement. The findings of an inflection at nearly identical field strength in the unstruck doped glass and the pure borosilicate glass is felt to be due to the presence of intermediate range order in the borosilicate glass.