Infrared spectroscopy of polycrystalline ZnO and ZnO:N thin films

Polycrystalline zinc oxide (ZnO) and nitrogen-doped zinc oxide (ZnO:N) films, about 1 μm thick, were grown by metalorganic chemical vapor deposition on crystalline silicon substrates. Infrared absorption measurements reveal a complex growth chemistry resulting in the presence of carbon, oxygen, and nitrogen-related functional groups not seen in single-crystal material. Noteworthy changes in the absorbance spectra that occur with the incorporation of nitrogen include a group of strongly absorbing bands around 1800 cm−1 and a band at 3020 cm−1 attributable to a N-H bond. These atomic configurations, in addition to the observed O-H bands around 3400 cm−1, provide insight into the difficulties of creating p-type ZnO through the incorporation of nitrogen.