Hydrogen doped zinc oxide films were prepared on glass substrate by using rf reactive magnetron sputtering method and the films were annealed in vacuum furnace. The reactive sputtering was carried out at the atmosphere of argon, oxygen and hydrogen. The gas composition of hydrogen was changed from 0% to 24%. In order to ionize the doped hydrogen atoms, the as-deposited films were annealed at 500℃, for 1 hour.
Highly conductive and transparent hydrogen doped ZnO thin films were prepared on glass substrates by using rf reactive magnetron sputtering from zinc target. The reactive sputtering gas was composed of argon, oxygen and 0~24% hydrogen. The effects of a hydrogen on the structural, electrical and optical properties of ZnO thin films were investigated in detail. There was a close relationship between electro-optical properties and structural properties. Using X-ray diffraction analysis, we could find that the c-axis was highly oriented perpendicular to the substrate in the range of 0~8% hydrogen, but the (0002) preferred orientation was degraded and the direction of grain growth was changed from (0002) to (1010)(1011)(1120) etc. as hydrogen content increased above 8%. And cross-sectional SEM images showed that colummar structure was well developed in ZnO thin films to some limit of hydrogen content (8% hydrogen) but, higher than the limit, secondary nucleation occurred and grain boundary density sharply increased. These increase of grain boundary density caused the electro-optical properties of ZnO thin films to degrade because grain boundaries act as trap sites lowering the mobility of free carriers. In addition, we heat treated the as- deposited hydrogen doped zinc oxide films for ionization of hydrogen atoms and recrystallization of the films. After heat treatment, c-axis orientation of ZnO films, Which are evaluated by full width at half maximun {FWHM} of XRD peak, was enhanced and grain boundary density decreased. As a result, the resistivity was lowered to the value of $10^{-3}Ωcm$ and the transmittance was improved to about 88% in visible wavelength region on optimum condition (8% hydrogen addition, 500℃, 1hr heat treatment in vacuum furnace), which was the highest value yet reported for ZnO films doped with hydrogen.
