Disentangling topographic contributions to near-field scanning microwave microscopy images
Samuel Berweger, Thomas M. Wallis, Pavel Kabos, Kevin J. Coakley
We develop empirical models to predict the contribution of topographicvariations to near-field scanning probe microwave microscopy (NSSM)images.In particular, we focus on |S11| images of a thin Perovskitephotovoltaic material and a GaN nanowire. The difference between the measured NSSM image and this prediction is our estimate of thecontribution of material property variations to the measured image. Prediction model parameters are determined from either a reference sample that is nearly free of material property variations or directly from the sample of interest. The parameters of the prediction model are determined by robust linear regression so as to minimize the effect of material property variations on results. For the case where the parameters are determined from the reference sample, the prediction is adjusted to account for instrument drift effects. Our statistical approach is fully empirical and thus complementary to current approaches based on physical models that are often overly simplistic.