PULSED-LASER DEPOSITION OF PATTERNED MULTILAYERS FOR HTS DEVICE FABRICATION

Pulsed laser deposition (PLD) has been used to deposit high quality mu ltilayer thin films of Permalloy/Au/YBCO onto (100) oriented substrate s of MgO and SrTiO3. These multilayer structures are currently being u sed to investigate the effect of the injection of polarized electrons on the order parameter of high temperature superconducting (HTS) thin films. To observe this effect, thin films with sharp interfaces (to mi nimize spin scattering) and low contact resistance will be required. T he morphology and structure of the deposited films has been investigat ed using scanning electron microscopy and x-ray diffraction, respectiv ely. The electrical properties (T-c and J(c) (77 K, B = 0)) were measu red for both unpatterned and patterned films. Films were patterned usi ng both wet chemical and ion beam (Ar+, 1 KeV) techniques. Unpatterned films were characterized inductively as having T-c's > 88 K and J(c)' s > 1 MA/cm(2). Wet chemical etching resulted in films with slightly r educed T-c's and J(c)'s similar to 10(3) - 10(4) A/cm(2) however, no r eduction in T-c or J(c) was observed for dry etching. A lift off proce dure using PMMA/Cu has been explored to define smaller (similar to 400 mu m) features. Extremely low contact resistance's (< 10(7) Omega cm( 2)) have been measured for Au films deposited by PLD onto YBCO. The lo w contact resistance is attributed to the high kinetic of the Au parti cles. These device structures can be used to develop simple HTS based transistors.