Role of the oxygen atomic beam in low-temperature growth of superconducting films by laser deposition

An oxygen jet placed near the target during plasma-assisted laser deposition produces a strong atomic oxygen beam with kinetic energies of 5.6 eV, simultaneous with the laser-induced atomic beams of Ba, Cu, and Y from the target. All atomic beams can be well characterized by a supersonic expansion mechanism. The behavior of the velocity distributions was studied as a function of the distance from the target and laser energy fluence. A target-substrate separation of 7 cm was found to be optimum in terms of producing the best as-deposited films. At that distance, the velocity distributions of all atomic beams become nearly the same.