Variability of atomically precise tunnel junctions

Donor devices fabricated in silicon using the scanning tunneling microscope (STM) are used as a discovery platform for everything ranging from quantum bits to ultra-efficient tunnel field effect transistors because the underlying hydrogen lithography step can be performed with atomic precision. However, the resultant devices are not necessarily atomically perfect. Here, we examine the reliability of STM-fabricated tunnel junctions, a basic element of the many of the devices and circuits fabricated with this technique. Low-temperature electrical transport measurements are used to characterize how similar nominally identical tunnel junctions behave, compared to tunnel junctions with intentionally different geometry. This work was supported by the Laboratory Directed Research and Development Program at Sandia National Laboratories, and was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. DOE, Office of Basic Energy Sciences user facility.