STRUCTURAL AND DIELECTRIC PROPERTIES OF (BaTiO_3/SrTiO_3)_(15) SUPERLATTICES GROWN BY MOCVD

摘要

(BaTiO_3/SrTiO_3)_(15) superlattices were grown by metal organicchemical vapor deposition (MOCVD) on <001> oriented LaAlO_3 and Nb-doped SrTiO_3 substrates. The source was a pulsed liquid-injection delivery system, with a unique precursors solution for each compound. The thickness of the layers was controlled by dusting the amount of liquid injected. Different sets of samples were prepared with varying interlayer thickness. The satellite peaks observed on the X-ray diffraction patterns indicate a superlattice structure. High-angle diffraction using X-ray synchrotron radiation was used to assess the structural and chemical disorder and the interface state with respect to the ideal effect-free superlattice. Electrical measurements were performed on the multilayers, using the SrTiO_3:Nb substrate as a bottom electrode. As the period of the (BaTiO_3/SrTiO_3)_(15) superlattices increases (and also the total thickness), the dielectric constant increases. It reaches a value of 620 for (BaTiO_3 36 u.c./SrTiO_3 36 u.c.)_(15)