dc and microwave resistivities of SrRuO3 films deposited on SrTiO3

• Published in: Journal of applied physics 2003-01, Vol.93 (2), p.1291-1297
• Main Authors: Rundqvist, P., Vorobiev, A., Gevorgian, S., Khamchane, K., Ivanov, Z.
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.1530723

Epitaxial SrRuO3 thin films on (001) SrTiO3 substrates grown by pulsed laser ablation at deposition temperatures ranging between 690° and 810 °C have been examined. The correlations between dc and microwave resistivity, microstructure, and surface morphology are obtained. According to the x-ray measurements the structure of all films is a mixture of highly oriented domains of strained SrRuO3 phases with different lattice parameters. The films grown at 780 °C consist mainly of orthorhombic phase I with a bulk lattice parameter close to the orthorhombic single crystal and reveal same resistivity values of 270 μΩ cm for both dc and microwave. Films obtained at other deposition temperatures contain a larger amount of orthorhombic phase II, with extended bulk lattice parameters and dc resistivity increases up to 1700 μΩ cm for the lowest deposition temperature. The corresponding microwave resistivity values are 50% higher than the dc ones. The dc resistivity of SrRuO3 films is in inverse proportion to the intensity of the (220) refection from orthorhombic phase I. The orthorhombic phase I domains reveal higher crystallinity (FWHM values are about 0.2°) and lower out-of-plane strain (0.4%) than corresponding values of the orthorhombic phase II domains (0.35° and 1.6%, respectively). According to AFM measurements the SrRuO3 films consist of a network of distinguishable islands separated by film areas with lower thickness. The islands consist mainly of orthorhombic phase II. At deposition temperatures more than 780 °C the film roughness is mainly due to holes formation caused, probably, by grain rotation and reevaporation of SrO chains. The difference between dc and microwave resistivity values is explained by influence of the film roughness.