  We have investigated the H2 pressure-dependent (from vacuum to 20 bar)
current-voltage characteristics of ZnO thin films prepared by spin coating
method. The gas pressure effect on conductance (G) was subtracted using He gas.
The G increased as applying 2 bar of H2 pressure, and then it monotonously
decreased with the further increment of H2 pressure. Using X-ray diffraction
patterns and X-ray photoelectron spectroscopy before and after H2 exposure, we
found that the H2 spillover effect plays an important role in the variation of
G of ZnO film.
