Characterization of the field-effect addressable potentiometric sensor (FAPS)

The field-effect addressable potentiometric sensor (FAPS) is a surface potential sensor with the option of high spatial resolution. It is based on the ability to control the resistance of field-effect channels in thin semiconductor films with electrical potentials. Compared to arrays of standard field-effect transistors (FET), the number of required leads is drastically reduced by arranging the field-effect channels and underlying gate electrodes in a grid structure. In order to investigate the practicability of the physical concept, a test structure was built by using the epitaxial lift-off technique. It was demonstrated that the concept of the FAPS can be put into practice. The frequency dependence of the test structure was analyzed experimentally and theoretically. At a time resolution of 3 kHz, the potential sensitivity was found to be better than 150 μV.