Electron transition and electron-hole recombination processes in epitaxial BaTiO3 films with embedded Co nanocrystals

An epitaxial BaTiO3 (BTO) film with embedded Co nanocrystals (NCs) was prepared according to interfacial engineering. Compared with the polycrystalline matrix in previous NCs-matrix systems, the current single-crystal BTO matrix possessed no grains and grain boundaries. The NCs and interface between the NCs and BTO could be regard as the grains and grain boundaries in the NCs-matrix system, respectively. By modulating the size (D) of Co NCs and spacing (R) between the NCs, we achieved the tuneable band gap, Schottky barrier height, the width of potential barrier and well of the nanocomposites. The electron transition and electron-hole recombination processes was well clarified for the NCs-matrix system. An ideal model was provided for explaining the effects of the interaction for NCs, grains and grain boundaries on the photoelectricity nature of materials.