Highly conducting SrMoO3 thin films for microwave applications

Abstract

We have measured the microwave resistance of highly conducting perovskite oxide SrMoO3 thin film coplanar waveguides. The epitaxial SrMoO3 thin films were grown by pulsed laser deposition and showed low mosaicity and smooth surfaces with a root mean square roughness below 0.3 nm. Layer-by-layer growth could be achieved for film thicknesses up to 400 nm as monitored by reflection high-energy electron diffraction and confirmed by X-ray diffraction. We obtained a constant microwave resistivity of 29 μΩ·cm between 0.1 and 20 GHz by refining the frequency dependence of the transmission coefficients. Our result shows that SrMoO3 is a viable candidate as a highly conducting electrode material for all-oxide microwave electronic devices.

Molecular beam epitaxy growth of the highly conductive oxide SrMoO3

“…3(a)). A broad satellite was also observed next to the sharp peaks, which is likely Mo 4+ 3d emission of unscreened final states 9,10,28,29 . We also collected a spectrum at a lower photon energy (600 eV), which is more sensitive for the film near the surface, and observed additional features at 233.1 eV and 236.4 eV.…”

“…The room temperature (RT) resistivity ρ of singlecrystalline SrMoO 3 is as low as 5 µΩ cm, which is much lower than typical oxide materials 4 and is rather close to those of nearly free electron systems such as sodium and copper. The utmost feature of this oxide has stimulated intensive studies to grow epitaxial films [5][6][7][8][9] for applications, for example, electrodes between oxide interfaces 5,10 and transparent conductors 6,11 . Unfortunately, all the films, so far prepared by pulsed laser deposition (PLD) [7][8][9][10][11][12] or sputtering 5,6 , show rather poor resistivity (27-150 µΩ cm) than that of the bulk single crystal, possibly due to the presence of defects or inclusion of impurity phases.…”

“…The high-quality of the film is verified by X-ray diffraction (XRD) and angle resolved photoemission spectroscopy (ARPES) measure-ments. The film with the SrTiO 3 buffer layer exhibited an improved resistivity of 24 µΩ cm at RT as compared with the SrMoO 3 films by other techniques 5,[7][8][9]11,15,16 .…”

Chemical Control of Correlated Metals as Transparent Conductors

“…Dense ceramic targets of SrMoO 4 and CaMoO 4 were prepared via conventional solid state synthesis. A reducing environment of 2.5% H 2 in Ar was used at 0.3 mTorr in order to reduce the Mo 6+ oxidation state of the target to the Mo 4+ state of the targeted perovskite phase as demonstrated in previous reports . A nominal substrate temperature of 650 °C was used with a laser fluence of 1.3 J cm −2 at a rate of 1 Hz.…”

“…SrMoO 3 is a cubic perovskite (inset of Figure a) and is one of the most conducting metallic oxides with a room temperature resistivity of 5.1 μΩ.cm . Recent thin film studies have focused on its application for plasmonic and microwave technologies. To assess the influence of replacing 3d 1 V 4+ with 4d 2 Mo 4+ on the performance of correlated metal transparent conductors, we have grown SrMoO 3 films with a thickness of 47 nm and root mean square (RMS) surface roughness of 0.3 nm (Figure S1, Supporting Information) and studied their electrical transport and optical properties which are compared with density functional theory (DFT) calculations (Figure ).…”