Near-field microwave microscopy of nanostructured materials: modeling and experiment

Synthesis of novel material often times requires novel analysis and characterization techniques. The possibility of combining sputtering (SPU) and Atomic Layer Deposition (ALD) in the same chamber, Sputtering Atomic Layer Augmented Deposition (SALAD), has produced interesting meta-dielectric nanocomposite systems that have unique optical and electronic properties, which may find novel applications [1]. Scanning Microwave Impedance Microscopy (sMIM) is a relatively novel characterization tool which permits assessment of local impedance. More recently, the utilization of microwaves in the near field regime has been an exciting topic in the field of high-resolution microscopy. We were able to demonstrate 1 nm resolution using scanning Microwave Impedance Microscopy (sMIM) where a spontaneously forming water meniscus concentrated the microwave fields in small regions [2]. Here we analyzed numerically sMIM with Finite Element Method (FEM) to investigate complex metal-dielectric structures created in a SALAD system. sMIM measurements provide information on both real and imaginary parts of the reflected microwave signal, which can be associated with the local conductivity and permittivity. Yet, these quantities can be influenced by the local topography, so extraction of the electronic contribution is a challenge. In this work, we perform tip-surface distance scans in order to gain a better understanding of the substrate response and compare with the FEM results.