On Specific Capacitance of SIS Junctions

We have discussed possible reasons of scatter in the specific capacitance measurement results reported by different authors. This observed scatter of the measurement data at higher critical current densities (lower RnA values) could be due variation of the tunnel barrier thickness within the same junction realized in various laboratories. We have shown this through modelling of the tunnel barrier as discrete areas of n, n-1 and n+1 monolayers. This results in a spread of the SIS junction specific capacitance for the same current density. Also, the reported data difference could be a consequence of the high uncertainty of the measurement methods. We developed and demonstrated a measurement method proved to provide a high accuracy in characterization of SIS junction capacitance. At the conference, we will present modelling and the data for direct measurement of SIS junction specific capacitance and compare these data with the earlier reported measurements.