Conducting atomic force microscopy for Nanoscale tunnel barrier characterization
Kristine Lang, Dustin A. Hite, Raymond W. Simmonds, Robert McDermott, David P. Pappas, John M. Martinis
Increasing demands on nanometer scale properties of oxide tunnel barriers necessitate a consistent means to assess them at these lengths. Here we use conducting atomic force microscopy (CAFM) to characterize aluminum oxide (AlOx)barriers to be used in Josephson-junction qubits. We find the appropriate physical interpretation for CAFM is as a probe of local propensity for insulator breakdown. We consider the effect of imaging force to establish a statistically reproducible method to compare CAFM current maps. We present results for several AlOx samples demonstrating the potential of this technique.