Cross-beam pulsed laser deposition: General characteristic

Physical background of the operation of the cross-beam pulsed laser deposit ion (CBPLD) is considered. In this modification of PLD, gas-dynamic interac tion of two plasma plumes from separate targets is used for particulate eli mination from the plasma flux to the substrate. The interaction of the plas ma plumes by CBPLD in a vacuum was investigated with the help of ion collec tors and optical spectroscopy. A minimal plasma number density in the inter section region necessary for an efficient plume interaction amounts to appr oximate to1.4x10(15) cm(-3) in the geometry of the experiments. For the mat erials with relatively high evaporation rates, the plasma density in the pl ume intersection region is larger than this value during almost the entire plume existing time, and the ablated material can be effectively utilized f or the deposition of films. CBPLD demonstrates a very good effectiveness of the particulate removal from the plasma flux, and it is reasonable to sugg est that CBPLD is one of the most effective working methods for particulate suppression in PLD. The interaction of two plumes results in filtering out the most energetic ions and the slowest neutrals of the original plumes fr om the plasma flux to the substrate, in decrease of the average plasma part icle energy, and in increase of the degree of ionization of plasma up to mo re than 100%. Mechanisms responsible for these effects are analyzed. An asy mmetric CBPLD geometry is proposed that makes it possible to mix materials of different targets directly in the laser plasma with good control over fi lm composition. (C) 2001 American Institute of Physics.