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Revealing Ohmic versus Schottky junctions
Revealing Ohmic versus Schottky junctions
The contact between Si and Al is ohmic, and the contact between Si and gold is the Schottky junction. These two types of junctions show very different surface potential distributions across the junction.
Between Al and Si, the measured surface potential shows a slow envelope extending across a couple of microns, indicating a lack of barrier. Between Si and Au, a clear barrier is observed in the surface potential, it is a manifestation of the Schottky barrier.
The high spatial resolution of the PF-KPFM allows the study of these two types of barriers at a 10 nm scale under ambient conditions. For more details, please see our paper ACS Nano, 14, 4, 4839 (2020)
Another application of PF-KPFM is to reveal the surface polarization of ferroelectric materials. In this demonstration, the surface of a BaTiO3 plate is measured, and the variation of the surface potential is observed. The variation of the surface potential is due to the adsorption of charges due to different dipole orientations. For more details, please see our paper ACS Nano, 14, 4, 4839 (2020)
PF-KPFM is also useful to observe the presence of surface charge distributions. The figure on the left shows a surface potential map of a MAPbBr3 crystal surface with PbBr2 degradation. Accumulation of charge appears at the MAPbBr3 side close to the PbBr2. For more details, please see our paper Angewandte Chemie Int. Ed., 59, 16083 (2020)
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