Crystallographic investigation of Au nanoparticles embedded in a SrTiO${}_3$ thin film for plasmonics applications by means of synchrotron radiation

Self-organized monocrystalline Au nanoparticles with potential applications in plasmonics are grown in a SrTiO${}_3$ matrix by a novel two-step deposition process. The crystalline preferred orientation of these Au nanoparticles is investigated by synchrotron hard x-ray diffraction. Nanoparticles preferentially align with the (111) direction along the substrate normal (001), whereas two in-plane orientations are found with $[110]{SrTiO_3} : || : [110]{Au}$and$[100]{SrTiO_3} : || : [110]{Au}$. Additionally, a smaller diffraction signal from nanoparticles with the (001) direction parallel to the substrate normal (001) is observed; once again, two in-plane orientations are found, with $[100{]}_{SrTi{O}_3}\mathrm{\mid }\mathrm{\mid }[100{]}_{Au}$ and $[100]{SrTiO_3} : || : [110]{Au}$. The populations of the two in-plane orientations are found to depend on the thickness of the gold film deposited in the first step of the growth.