Doping nanocrystals by in situ layer-by-layer overcoating

We demonstrate that internally doped nanocrystals can be obtained by an in situ overcoating process. In the case of ZnSe doped with iodine, ZnSe cores are overcoated by interlaced iodine layers and ZnSe layers to incorporate the iodine atoms into the ZnSe matrix. Photoluminescence from the ZnSe band edge is gradually depressed, while emission from the deep-level recombination caused by iodine is dramatically improved up to fourfolds with increasing number of iodine/ZnSe overcoats. This result suggests that the impurity atoms are incorporated into the host matrix.