FORMATION OF ATOMIC-BEAMS AND DYNAMICS OF INSITU SUPERCONDUCTING FILM GROWTH BY PULSED-LASER DEPOSITION

Various issues on the in situ formation of superconducting Y-Ba-Cu-O (YBCO) thin films by pulsed-laser deposition are discussed. In particular, the formation of the various atomic beams by the pulsed laser, the question of oxygen incorporation during film growth, the transformation from the tetragonal to the orthorhombic phase, the nucleation dynamics and the nature of the interface layers between the YBCO film and the substrates are addressed. The availability of a strong oxygen atomic beam coming from both the target and the O2 ambient is a unique feature of pulsed-laser deposition. However, most of the physics of the dynamics in situ film formation, the tetragonal-to-orthorhombic transformation and interface reactions are also valid for other types of thin film and other deposition methods as well. It is shown that the technique of in situ resistance measurement is very powerful in obtaining information about the dynamics of the oxygenation process and the mechanisms of thin film growth and interface reactions. In particular, it yields information about the interface compound which is not achievable with other techniques.