Direct observation of the defect structure and structural interfaces in laser-deposited Y-Ba-Cu-O thin films

Abstract

One of the earliest applications of the newly discovered high temperature oxide superconductors is in the area of microelectronics, involving the fabrication of epitaxial thin films and heterostructures on suitable substrates. After examining several thin films deposition techniques, the pulsed excimer laser deposition technique has been found to yield films with excellent superconducting properties including a Tc of 90-91K, a superconducting transition width of less than 0.5°, transport critical currents of 5×106A/cm2 or higher and good microwave properties. The higher critical currents in the thin films, compared to bulk materials, have been attributed to the presence of a wide variety of structural defects that act as flux pinning centers. Hence, we have undertaken a systematic study of the atomic nature of the structural defects. In addition to high resolution electron microscopy(HREM), microdiffraction and analytical electron microscopy are being used to study the microstructure. Specifically, HREM is being carried out using the 1.6A point-to-point resolution and ±45° goniometric tilt capability of the Berkeley Atomic Resolution Microscope(ARM).