Fabrication of CuO2-plane-based high-temperature superconducting thin films by atomic layer controlled molecular beam epitaxy

Bi2Sr2Can−1CunOx (BSCCO) thin films and superconducting superlattices, (Bi2Sr2CaCu2Ox(2212)) l/ CuOy(2201))m, have been fabricated by the atomic layer controlled molecular beam epitaxy (MBE) method using an oxygen radical beam. During the deposition, the surface structure has been investigated by reflection high energy electron diffraction (RHEED) observation. For the BSCCO crystal growth, in spite of the three-dimensional growth of Ca/Cu layers, recrystallization was caused by Bi deposition and surface flatness was improved. Consequently, the layered crystal structure was completed by the Bi deposition. This fact indicates a unit cell growth mechanism. It was also demonstrated that this atomic layer controlled MBE method has great advantages to control the number of CuO2 planes in BSCCO and to fabricate the superconducting superlattices, (2212)l/(2201)m.