Atomic Force Microscopy is a type of scanning probe microscopy, with demonstrated resolution on the order of fractions of a nanometer, more than 1000 times better than the optical diffraction limit. The information is gathered by "feeling" or "touching" the surface with a mechanical probe. Piezoelectric elements that facilitate tiny but accurate and precise movements on (electronic) command enable precise scanning.
In our group we employ a Park NX10 AFM equipped with different modules allowing for multimodal AFM techniques. Upon request the instrument can be booked by external users.
We employ AFM to characterize different material properties of electronic materials with nano-scale resolution. The mechanical interactions with the surface allow us to acquire the surface topography and to position the tip in specific locations. Multimodal AFM techniques then employ additional modes of interaction between the tip and the sample. Relevant for electronic materials are the electrostatic interactions or the surface conductivity that are probed in Kelvin Probe Microscopy, Piezoelectric Force Microscopy or conducting AFM. Example multimodal images aquired in our group are shown on the left. Other AFM techniques that we employ are Force Spectroscopy to quantify elastic properties and electrochemical AFM to characterize solid liquid interfaces.
The development of new materials and devices for flexible electronics depends crucially on the understanding of how mechanical strain affects electronic material properties at the nano-scale. We developed a novel characterization approach that allows us to perform Scanning Kelvin Probe Microscopy (SKPM) on flexible electronic devices while they are deformed. SKPM is a unique technique for nanoelectronic investigations as it combines non-invasive measurement of surface topography and surface electrical potential. The formation of defects is easily identified in SKPM due to the abrupt variation in surface potential and build-up of high electronic fields to push carriers across defect regions. The technique provides us answers that help to develop novel semiconducting materials and devices that are more resistant to elastic deformations.
Recent related publications
Fazio, MARIA ANTONIETTA; Perani, Martina; Brinkmann, Nils; Terheiden, Barbara; Cavalcoli, Daniela, Transport properties of Si based nanocrystalline films investigated by c-AFM, «JOURNAL OF ALLOYS AND COMPOUNDS», 2017, 725, pp. 163 - 170 [articolo]
Cramer, Tobias; Travaglini, Lorenzo; Lai, Stefano; Patruno, Luca; De Miranda, Stefano; Bonfiglio, Annalisa; Cosseddu, Piero; Fraboni, Beatrice, Direct imaging of defect formation in strained organic flexible electronics by Scanning Kelvin Probe Microscopy, «SCIENTIFIC REPORTS», 2016, 6, pp. 1 - 9