TUNNEL BARRIER PROPERTIES OF OXIDIZED BISMUTH DROPLETS ON AL2O3

We discuss the tunnel barrier properties of oxidized ultrasmall Bi dro plets on and sandwiched within Al2O3. Scanning tunneling microscopy (S TM) and standard sandwich junction studies of these systems have revea led a consistent evolution of tunnel barrier parameters for the compos ite Bi2O3/Al2O3 barrier. We observe a systematic decrease in barrier h eight with increasing barrier width similar to the results for progres sively oxidized pure Al2O3 and other refractory oxides. Our results su ggest that STM, under appropriate conditions, can be employed to evalu ate and view the time evolution of the local characteristics of select ed tunnel-barrier systems. (C) 1996 American Institute of Physics.