Contatto di riferimento: Laura Basiricò
Partecipanti: Dr.Martina Perani
Abstract
Scanning Probe Microscopy is a very useful technique that provides a variety of information about the surface of materials. Atomic Force Microscopy (AFM) can be used to measure the morphology of a sample, the energy dissipation that occurs between the tip and surface, the local conductivity and many other features.
Topography images were obtained with the AFM in tapping mode. Samples with very different morphology were imaged and the same subsequent analysis has been applied to all of them. The analysis merges together different approaches studied in literature and aims to combine the results for gaining a deeper insight on surface properties. The results underline that this methodology can be of general use and can be applied for a wide range of materials.
The Height – Height Correlation Function (HHCF) is used within this framework in order to evaluate different parameters of the surfaces under investigation, such as roughness, lateral correlation lengths and wavelengths. The latter two, in particular, are related to the size and distribution of the grains.
A watershed algorithm is also applied to the AFM images, allowing an efficient marking of the grains and the evaluation of different properties of the structures, such as the size, area and volume, providing a better knowledge of the characteristics of the analyzed surfaces.
Conductive-AFM (c-AFM) is a tool employed to characterize the local conductivity of a material at the nanoscale. Different layers for application in photovoltaics have been analyzed and regions of the samples with different local conductivity have been evidenced. Local current-voltage spectroscopies have been measured with a conductive probe and different slopes of the curves have been observed, reflecting the different local conductivities present on the layers.