Role of substrates for heteroepitaxial growth of low room-temperature resistivity RuO₂ thin films deposited by pulsed laser deposition

Conductive RuO₂ thin films were grown on different substrates by pulsed laser deposition. Films deposited on MgO are of (110) orientation and of polycrystalline nature, while highly crystalline RuO₂ films can be heteroepilaxially grown on LaAlO₃ and yttria-stabilized zirconia (YSZ) substrates under proper processing conditions. The crystalline RuO₂ thin films show metallic resistivity versus temperature characteristics and have a room-temperature resistivity of 35±2 μΩ cm. A residual resistivity ratio (ρ_{300 K}/ρ_{4.2 K}) of around 5 has been achieved for the RuO₂ thin films grown at a substrate temperature of 700 °,C on both LaAlO₃ and YSZ.