The formation and electrical properties of discrete islands in discont
inuous Au films on Si(111) were studied with a scanning tunneling micr
oscope (STM). Ohmic electrical contact between the STM tip and isolate
d gold islands was established and I-V characteristics of the Au-Si ju
nctions were measured. A typical Schottky diode behaviour with idealit
y factor close to 1 was observed. The STM appears to be an appropriate
probe for electrical measurements of nano-scale diodes.