Cynthia Edney

Solution deposition planarization of long-length flexible substrates

Solution deposition planarization (SDP) is studied for preparing smooth flexible substrates in multimeter lengths. We demonstrate 0.5 nm rms surface roughness starting from unpolished metal tapes and a correlation of substrate roughness with the texture of subsequent ion-beam aligned films. Surface roughness reduction in SDP is modeled via film shrinkage during solution deposition and a residual roughness based on film thickness. Use of solution deposited a-Y2O3 to planarize substrates prior to ion-beam textured MgO growth shows an in-plane texture of MgO down to 4°. Utilizing these templates, we demonstrated superconducting YBa2Cu3Oy coated conductors with critical current densities of 2.8–4.0 MA/cm2 at 75 K.

Electrical and optical characterization of the metal-insulator transition temperature in Cr-doped VO2 thin films

The effect of Cr doping on electrical and optical properties of CrxV1−xO2 thin films across the metal-insulator transition has been studied. Resistance, Hall effect, and infrared reflectance show that Cr doping systematically increases the transition temperature Tc from 59 °C at x = 0 to 70 °C at x = 0.11 with similar transition width and hysteresis from DC to infrared, but the effect appears to saturate. The conductance contrast between insulating and metallic phases decreases with Cr doping. The effects of carrier density and mobility changes across Tc will be discussed.

Advanced titania buffer layer architectures prepared by chemical solution deposition

Chemical solution deposition (CSD) was used to grow high-quality (100) oriented films of SrTiO3 (STO) on CSD CaTiO3 (CTO), Ba0.1Ca0.9TiO3 (BCT) and STO seed and template layers. These template films bridge the lattice misfit between STO and the nickel–tungsten (NiW) substrate, assisting in dense growth of textured STO. Additional niobium (Nb) doping of the STO buffer layer reduces oxygen diffusion which is necessary to avoid undesired oxidation of the NiW. The investigated templates offer suitable alternatives to established standard buffer systems like La2Zr2O7 (LZO) and CeO2 for coated conductors.