Structural changes stimulated by ultraviolet (UV) irradiations of sol-gel-d
erived indium oxide thin films were investigated. Illumination of incoheren
t UV photons (4.9 eV) from a low-pressure mercury lamp resulted in formatio
n of crystalline indium metal. Irradiation of coherent UV beams from an ArF
excimer laser (6.4 eV) and from the fourth harmonics of a Nd:YAG laser (4.
7 eV) was found to be effective in the crystallization of indium oxide, acc
ompanied by a decrease in the sheet resistance. The lowest resistance witho
ut a reduction of transmission in the visible region was achieved with a 6.
4 eV laser beam at a fluence over 10-20 mJ cm(-2) shot(-1). The results of
x-ray photoelectron spectroscopy revealed that charge transfer from O2- to
In3+ was induced by the incoherent and the coherent UV photons. The partial
reduction with the incoherent illumination and the crystallization with th
e laser irradiation are tentatively assumed to be due to electronic excitat
ions in the amorphous network. (C) 1999 American Institute of Physics. [S00
21-8979(99)05401-8].