Excitonic Crystal and Nanotechnology

The role and application of bound excitons in nanoscience and technology are discussed in this chapter. Bound excitons are well studied in semiconductors, especially in gallium phosphide doped by nitrogen (GaP:N). Doping of GaP with N leads to isoelectronic substitution of the host P atoms by N in its crystal lattice and to creation of the electron trap with a giant capture cross-section. Therefore, any non-equilibrium electron in the vicinity of the trap will be captured by N atom, attracting a nonequilibrium hole by Coulomb interaction and creating the bound exciton short-lived nanoparticle with the dimension of the order of 10nm (it is the Bohr diameter of bound exciton in GaP:N). Note, that none of nanotechnology methods are used in creation or selection of dimensions of these nanoparticles – only natural forces of electron-hole interaction and electron capture by the traps are necessary for creation of these nanoparticles. As the result we get something like neutral short-lived atom analogue a particle consisting of heavy negatively charged nucleus (N atom with captured electron) and hole. So called “zero vibrations” do not destroy possible solid phase of bound excitons having these heavy nuclei that gives an opportunity to reach their crystal state short-lived excitonic crystal.