To shed light on this question, researchers at ETH Zuerich have used low-temperature scanning gate microscopy to examine a nanostructure fabricated by local anodic oxidation. A metallic tip is scanned over the structure and by keeping the tip voltage fixed, it is possible to move the electrical potential induced by the tip to any position on the structure. No current flows from the tip to the sample.

Design tool

Using this technique, the team can resolve the position at which leakage currents occur and answer important questions such as: do leakage currents occur homogenously along the whole boundary of two neighboring terminals? Where on such boundaries are leakage currents most likely to occur? Do leakage currents occur most likely at the smallest parts of the nanostructure?

The group has found that in a nanostructure fabricated by local anodic oxidation, leakage currents are most likely to occur at crossings between oxide lines and explain this phenomenon based on the details of the fabrication process. With this knowledge, the researchers can suggest ways of improving the fabrication process. In the future, this may allow developers to build nanostructures that minimize leakage and maximize tunability.

More information can be found in the journal Nanotechnology.