Effect of growth conditions on surface morphology and photoelectric work function characteristics of iridium oxide thin films

The effect of thermal growth conditions on the morphology and surface work function of iridium oxide thin films grown by annealing Ir thin films in an O-2 ambient is presented. The samples were analyzed using x-ray diffractio n, x-ray photoelectron spectroscopy, atomic force microscopy, and photoelec tric work function measurements. It is found that, with increasing temperat ure, IrO2 changes from (110) oriented to a mixture of (110) and (200) durin g the oxide growth. This is manifested as a sharpening of the photoelectric energy distributions at 800 degrees C. The surface work function was deter mined to be 4.23 eV using ultraviolet photoelectron spectroscopy. X-ray pho toelectron spectroscopy analysis shows that IrO2 starts to form at 600 degr ees C accompanied by surface roughening. Annealing the Ir film at 900 degre es C in O-2 ambient leads to almost complete desorption of the film. (C) 19 99 American Institute of Physics. [S0003-6951(99)02310-4].