Vacuum ultraviolet annealing of thin films grown by pulsed laser deposition

The effect of a post-deposition annealing treatment in I bar of oxygen at m oderate temperatures (< 450 degrees C) under illumination by vacuum ultravi olet (VUV) radiation emitted by an excimer lamp upon thin ZrO2 and hydroxya patite (HAp) films grown by the pulsed laser deposition (PLD) technique was investigated. The optical and structural properties of the films were impr oved by this treatment, the lower the deposition temperature and, according ly, the poorer the initial characteristics, the more significant the improv ements. The combination of these two techniques allowed us to obtain at tem peratures below 350 degrees C highly textured (020) ZrO2 films, exhibiting optical absorption coefficients lower than 5 x 10(2) cm(-1) and high refrac tive index values of around 2.25 in the visible region of the spectrum. The VUV treatment was also beneficial for the partially crystalline HAp layers containing tetracalcium phosphate and calcium oxide phases grown by the PL D technique under a low pressure oxidising atmosphere of only 10(-5) torr w ithout any water vapours. After the VUV-assisted anneal, the crystalline st ructure and the stoichiometry greatly improved while the percentage of the other crystalline phases initially present was many times reduced. (C) 1999 Elsevier Science B.V. All rights reserved.