Congruent Evaporation and Epitaxy in Thin Film Laser Ablation Deposition (Lad) of Rare Earth Transition Metal Elements and Compounds

Abstract

ABSTRACTLaser ablation deposition (LAD) is a versatile thin film preparation technique which has been slowly developing for a number of years, and is currently receiving a lot of attention as demand increasingly exploits its advantages over other established techniques. Apart from its simplicity, one of its main advantages is the possibility of congruently evaporating any solid compound target, be it metal or insulator, due to the extremely high energy and instantaneous power densities attainable with pulsed lasers (up to 50 Jcm−2 and 1012 Wcm−2 for picosecond pulses). In this paper, we report on tests for both congruent evaporation in LAD of a number of rare earth - transition metal intermetallic compounds including Nd2 Fe1 3 B, Yzn0.7, Yni3, Y2 Fe15 and Yni5 for different preparation conditions (using a Nd:YAG laser λ = 1064, 532, 355 nm, τ = 35 ps and 20 ns) and on the epitaxial growth of Yni5 and W on monocrystalline sapphire substrates. Optical and electron microscopy were used to examine film morphology while congruent evaporation was confirmed using x-ray microprobe analysis. In-situ RHEED revealed good epitaxy of the films deposited on sapphire, with the hexagonal diffraction patterns obtained for YNis being identical to those of an YNi 5 reference single crystal.