Cross-beam pulsed laser deposition: General characteristic

Abstract

Physical background of the operation of the cross-beam pulsed laser deposition (CBPLD) is considered. In this modification of PLD, gas-dynamic interaction of two plasma plumes from separate targets is used for particulate elimination from the plasma flux to the substrate. The interaction of the plasma plumes by CBPLD in a vacuum was investigated with the help of ion collectors and optical spectroscopy. A minimal plasma number density in the intersection region necessary for an efficient plume interaction amounts to ≈1.4×1015 cm−3 in the geometry of the experiments. For the materials with relatively high evaporation rates, the plasma density in the plume intersection region is larger than this value during almost the entire plume existing time, and the ablated material can be effectively utilized for the deposition of films. CBPLD demonstrates a very good effectiveness of the particulate removal from the plasma flux, and it is reasonable to suggest 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 from the plasma flux to the substrate, in decrease of the average plasma particle energy, and in increase of the degree of ionization of plasma up to more than 100%. Mechanisms responsible for these effects are analyzed. An asymmetric CBPLD geometry is proposed that makes it possible to mix materials of different targets directly in the laser plasma with good control over film composition.