Determination of density and specific surface area of nanostructured zinc oxide films by X-ray fluorescence and scanning electron microscopy

Films of zinc oxide (ZnO), with thickness ranging from 100-400 nm and perforated by pores, are fabricated using variable angle magnetron sputtering and characterized using X-ray fluorescence (XRF) and scanning electron microscopy (SEM). The nanopores of such films make them suitable for gas-sensors and other applications, but the effective surface area for films this thin cannot be measured easily using conventional techniques. We propose and apply a method that uses XRF to measure the bulk film density and SEM to determine the size and distribution of pores on the sample exterior. Combining these results, we determine the specific surface area of the crystalline ZnO films that is up to 11.8 m 2 /g. This is a viable approach for characterizing the ZnO nanocolumnar ultrathin films.