Nanooptics and photonics

Annealing effect in ZnO/Si heterostructures doped with rare earth ions (Eu and Tb).

C. Leroux1, D. Pelloquin1, X. Portier2, Z. Zhuchenko3, A. Zolotovsky 3, G.G. Tarasov3
1CRISMAT, UMR CNRS 6508, ENSICAEN, Normandie Université, 6 Boulevard du Maréchal Juin, 14050 Caen Cedex 04, France
2CIMAP, CEA, UMR CNRS 6252, ENSICAEN, Normandie Université, 6 Boulevard du Maréchal Juin, 14050 Caen Cedex 04, France
3V. Lashkaryov Institute of Semiconductor Physics of the NAS of Ukraine, 45 Prospect Nauky, 03028 Kyiv, Ukraine 
E-mail:tarasov@isp.kiev.ua
ZnO belongs to II-VI semiconductors with an electrical conductivities of about 7x10-7 S.cm-1 at room temperature in case of  a nanostructured thin film growing up to 10-4 S.cm-1 for higher temperatures. If this film is doped with Al, its electrical conductivity significantly increases. As a result, thin film ZnO structures are widely used for the PL and photovoltaic applications. The doping of ZnO thin films with rare earth (RE) ions allows to get original and alternative white LEDs structures or to enhance the efficiency of a solar cell. Here we present the result of detailed structural analysis of Eu/Tb codoped ZnO thin films annealed at different temperatures. Analysis was performed using PEDT data combined with atomic STEM-HAADF imaging and spectroscopic approaches (EDX, EELS). The theoretical calculations (PL modeling) based on the method of multielectron molecular orbitals are applied. This method allows, in fact, to reproduce to spectral lineshape of rare earth emission for different crystalline surrounding, thus facilitating understanding the observed changes in the PL experimental data.