Ultrathin SrTiO3 films prepared by chemical vapor deposition on Nb-doped SrTiO3 substrates

The SrTiO3 ultrathin film capacitors were realized on Nb-doped single-crystal SrTiO3 substrates by chemical vapor deposition. The leakage current density of 10.4 nm thick SrTiO3 thin-film capacitor was below 1×10−8 A/cm2 in the applied voltage range of −1.8 to +0.45 V, and its SiO2 equivalent thickness was 0.48 nm. The relative dielectric constant was over 160 for SrTiO3 thickness above 20 nm, but it decreased for SrTiO3 thickness below 20 nm. Dependence of leakage current on SrTiO3 film thickness was slight. These results could be explained by the existence of applied electric field concentration near the SrTiO3/electrode interface.