MOCVD and PE-MOCVD of HTSC thin films

Abstract

High quality YBaCuO and TlBaCaCuO thin films were deposited on MgO, LaAlO3 and Ag substrates by standard thermal and plasma enhanced MOCVD. The growth was done in inverted vertical reactors designed to achieve stagnation point flow and extremely uniform deposition rates were achieved (±0.5%) over large areas (5 cm2). The films were characterized by SEM‐EDX, x‐ray diffraction, four point probe, critical current density, dynamic impedance, and surface resistance measurements. C‐axis oriented films with resistive transitions (R≤0.1 μV/cm) exceeding 110 K and 85 K were routinely obtained for the Tl‐ and Y‐based superconductors grown on single crystal substrates. The best films had inductive transition widths less than 1 K and critical current densities (ambient field) as high as 106 A/cm2 at 77 K. The surface resistance of the films was measured using a cavity end wall replacement method and values as low as 10 mΩ were observed at 78 K and 35 GHz on both LaAlO3 (100) and Ag substrates.