V. Christou et al., High resolution x-ray photoemission study of plasma oxidation of indium-tin-oxide thin film surfaces, J APPL PHYS, 88(9), 2000, pp. 5180-5187
The influence of plasma oxidation and other surface pretreatments on the el
ectronic structure of indium-tin-oxide (ITO) thin films has been studied by
high resolution x-ray photoemission spectroscopy. Plasma oxidation compens
ates n-type doping in the near surface region and leads to a reduction in t
he energy of plasmon satellite structure observed in In 3d core level spect
ra. In parallel, the Fermi level moves down within the conduction band, lea
ding to a shift to low binding energy for both core and valence band photoe
mission features; and the work function increases by a value that correspon
ds roughly to the core and valence band binding energy shifts. These observ
ations suggest that the conduction band of ITO is fixed relative to the vac
uum level and that changes of work function are dominated by shifts of the
Fermi level within the conduction band. (C) 2000 American Institute of Phys
ics. [S0021-8979(00)04621-1].