PULSED EXCIMER-LASER ETCHING OF LA0.75CA0.25MNOX THIN-FILMS

Pulsed (lambda=248 nm, pulse width=20 ns) KrF-excimer-laser-induced et ching of La0.75Ca0.25MnOx (LCMO) thin films exhibiting giant magnetore sistance (GMR) has been studied. The variation of etch depth as a func tion of the number of laser pulses shows a linear dependence in the fl uence range between 0.15 and 4 J cm(-2). The threshold fluence for abl ation is found to be 0.07 J cm(-2). The photoetching process is seen t o follow the Beer-Lambert's relation based on a linear absorption mode l with an absorption length of 28.3 nm. The nanomorphology of the lase r etched surface as revealed by atomic force microscopy shows signific ant improvement in the surface smoothness of the deposited films for e tching at low energy densities (typically 0.17 J cm(-2)) and enhanced roughness at higher energy densities (typically 0.86 J cm(-2)). Change s in the resistivity and GMR effect due to laser treatment are also ex amined. (C) 1995 American Institute of Physics.