Spin splittings in nanostructures without inversion symmetry

In a crystal lacking inversion symmetry, in the presence of spin-orbit interaction, the spin degeneracy is in general removed at k not equal 0 even in the absence of an external magnetic field. Such is the case for bulk III-V semiconductors having the zincblende structure. In nanostructures having a reduced symmetry with respect to the bulk, additional zero-field spin-splitting mechanisms are allowed. The interplay between the different spin-orbit interactions is thoroughly investigated and the relevance of the spin-splittings for excitonic properties is addressed. In particular, the competition between intraexciton exchange and single particle spin flips in the relaxation of the exciton luminescence polarization is analysed