Effect of Water Vapor in Thermal Diffusion of Indium into ZnO Nanoparticles

Thermal diffusion of indium (In) into ZnO nanoparticles (NPs) were examined to decrease sheet resistance values of ZnO NP layers sprayed on quartz substrates. NP layers made of as-synthesized ZnO NPs exhibited extremely high sheet resistance values. On the other hand, NP layers made of ZnO NPs with In diffusion, the sheet resistance showed large variation, and in particular, it decreased significantly showing a strong correlation with the water vapor contents in the gases during thermal diffusion. The sheet resistance value decreased down to the order of 105 Ω sq−1 (minimum value of 6 × 105 Ω sq−1). From X-ray diffraction, energy dispersive X-ray spectroscopy and photoluminescence analyses, the effects of the surface defects of ZnO NPs and the ambient water vapor in thermal diffusion process were discussed.