Ultra thin film of Bi cuprate grown by a low temperature molecular beam epitaxy

Abstract

Structural and physical properties of ultra thin films of Bi 2Sr 2CuO 6 and Bi 2(Sr,Ca) 3Cu 2O 8 formed by a low temperature (<673 K) molecular beam epitaxy (MBE) method using 10 −5Pa of NO 2 as an oxidant are presented. On the substrates with less than 3% lattice mismatch, epitaxial growth from the substrate surface is realized, resulting in the formation of strained lattices. For the substrate with a big lattice mismatch of 10% (MgO), the observed lattice constants were similar to that for the bulk material. A superconducting transition with the onset Tc of 90K and the zero-resistance of 40K was obtained for the Bi 2(Sr,Ca) 3Cu 2O x/MgO(100) by post annealing at 1093K with O 2. The optical absorption of the film indicate that annealing with O 2 gives rise to an increase in the carrier concentration.