EXCITONS IN CDTE QUANTUM WIRES WITH STRAIN-INDUCED LATERAL CONFINEMENT

Using a two-step epitaxial growth process we have fabricated nanometer -scale quantum wires through the modulation of the in-plane lattice co nstant of a [110] CdTe/CdxZn1-xTe quantum well grown on top of a [001] CdTe/CdxZn1-xTe strained superlattice. With respect to the unmodulate d [110] quantum well, the photoluminescense of these quantum wires pre sents a large redshift which depends strongly on the excitation densit y. Thr results compare very well with a theoretical model assuming no strain relaxation in the structure. In this framework, we show that (i ) the hole is confined via the Coulomb attraction of the electron and not via the valence-band offset, and (ii) due to the nonlinearity of t he piezoelectric coefficient in CdTe, a lateral piezoelectric field is present in these strained modulated [110] wires.