Dynamic EFM spectroscopy studies on electric force gradients of IrO₂ nanorod arrays

The spectroscopy mode of the electric force microscope (EFM) was used to study the variation of the local electric force gradients above CVD-grown thin films of iridium oxide field emitters. The spacing, radius, and morphology of the nanoprotrusions were observed to change significantly within the sample. In this research, we present the first EFM study of the electric force gradients above the iridium oxide (IrO2) nano-arrays. The electric force gradients are measured with the amplitude change of the EFM cantilever vibration operated in air using the lift-mode technique. Regions in the array with nanorods of largest spacing yield the largest force gradients, but a relatively large non-uniformity of the force gradients is observed. However, relatively homogeneous force gradients were obtained in areas with nanorods of smallest radius and densest population (flower-cluster zone).