Diamond thin films were grown on diamond (10 0) substrates in oxygen atmospheres by pulsed laser deposition (PLD) using a graphite target. In the optimum oxygen pressure of 5 x 10(-2) Tort, the sp(2) bonding fractions can be etched away preferentially and the spa bonding fractions remain predominantly on the substrate. At substrate temperatures lower than 400 degreesC, amorphous carbon generates. At higher than 400 degreesC, diamond crystallites begin to generate in the amorphous carbon. At the suitable substrate temperatures between 550 and 650 degreesC, single-phase diamond films consisting of diamond crystal with diameters of 1-5 mum could be grown. Based on the results, the growth process of diamond thin film by PLD is considered. (C) 2002 Elsevier Science B.V. All rights reserved.