Quantum-confined Franz-Keldysh effect in CdTe quantum dots in glass

V. Esch, G. Khitrova, H.M. Gibbs and Xu Jiajin,

There has been considerable interest in the electric-field dependence of optical properties of semiconductor quantum-well structures. We have extended these electric-field studies to quantum dots, i.e., to structures confined in all three dimensions. The new CdTe quantum-dot glass first reported here is especially suited for electric-field effects because of the large Bohr radius, aB = 73 Å; it has as many as six quantum-confinement peaks in the absorption spectrum with dot radii, ro = 36 Å. The observed changes in the absorption spectrum (see top figure) are interpreted to arise mainly from a red shift of the lowest transition and the redistribution of the oscillator strength as forbidden transitions are opened up by the symmetry-breaking action of the external field. This interpretation is made plausible by a spherical-coordinate-system calculation (upper figure), that neglects the Coulomb interaction; it is similar to that for cuboidal structures by Miller, Chemla, and Schmitt-Rink, and predicts a differential absorption spectrum in good qualitative agreement with the data.

Log in or become a member to view the full text of this article.

This article may be available for purchase via the search at Optica Publishing Group.
Optica Members get the full text of Optics & Photonics News, plus a variety of other member benefits.

Add a Comment