DIAGNOSTICS OF YBA2CU3O7-DELTA LASER PLUME BY TIME-OF-FLIGHT MASS-SPECTROMETRY

The time-of-flight mass spectrometry has been used to investigate the formation of charged species in the laser ablation of YBa2Cu 3O7-δ (YBCO) target. Mass spectra were taken both in high vacuum and in oxygen environment for two values of the laser energy density (0.74 and 2.5 J cm-2). The analysis of the charged species in the plume has been carried out as a function of the distance between the target and the spectrometer axis and the relative abundance of Cu, Y, Ba, CuO, YO, and BaO ions has been measured and discussed. In this paper the formation of heavy species and YBCO clusters is also discussed. The plume range has been evaluated as a function of the absorbed energy at a distance from the target plane close to that one at which good quality high Tc superconducting films are obtained, the plume composition has been found to be characterized by the presence of a series of oxide clusters originating from the interaction between the ablated material and the environmental oxygen. This confirms that the interaction between the plume and the environmental oxygen plays an important role both in the formation of heavy charged species and in the capture of the oxygen required to obtain the correct stoichiometric composition of the deposited film. © 1994 American Institute of Physics.