Growth of Ba1-xKxBiO3 thin films by molecular beam epitaxy

Single-crystalline Ba1-xKxBiO3 (BKBO) films with x between 0 and 0.54 are prepared on SrTiO3(1 0 0) substrates by molecular beam epitaxy (MBE). The key to the MBE growth of BKBO is the reproducible deposition of K, which is achieved by using an alkaline metal dispenser (K2CrO4 with a reducing agent) to make the K source easy to handle, and also by using atomic absorption spectrometry to provide reliable K flux rate control. The films are superconducting for similar to0.31 less than or equal to x less than or equal to similar to0.54. The best film (x = 0.46) shows T-c(onset) = 24.5 K, T-c(end) = 24 K, rho(300 K) similar to 220 muOmega cm, and rho(30 K) similar to 150 muOmega cm. (C) 2004 Published by Elsevier B.V.