Atomic silicon wires: dopant mediated charging characterization

CMOS technologies are approaching their performance limits. Atomic silicon electronics are poised to provide the next-generation of devices. This beyond CMOS platform consists of exactingly patterned dangling bond (DB) circuitry on hydrogen passivated silicon (H-Si).¹ Many passive and active components can be made of DBs, here we investigate atomic silicon wires. We employ a recent dopant based charge sensing procedure in conjunction with non-contact atomic force microscopy to study the charging behavior of atomically fabricated DB wires on H-Si (100) 2x1. On its own, this method can be used to rapidly detect local net charge with single electron sensitivity; coupled with AFM, it can drastically improve confidence in data interpretation.² In this scheme, a single DB sensor is employed to detect a sharp step in its I(V) spectroscopy due to the ionization of a nearby arsenic dopant. As charged DBs are fabricated nearby, local band bending shifts the dopant ionization voltage which can act as a charge sensor. Wires, both parallel and perpendicular to the dimer direction were systematically lengthened and studied using this method. The charging behavior for various lengths of wire, and novel observations, such as a length dependent flip flop in electron occupation for perpendicular wires are demonstrated. This method and these results will be used to improve the characterization of DB structures and will eventually be directly compared to theory to improve the modeling of DB circuitry.

1. Huff, T., Labidi, H., Rashidi, M., Livadaru, L., Dienel, T., Achal, R., Vine, W., Pitters, J., & Wolkow, R. A. (2018). Binary atomic silicon logic. Nature Electronics, 1(12), 636–643. https://doi.org/10.1038/s41928-018-0180-3
   
   Achal, R., Rashidi, M., Croshaw, J., Huff, T. R., & Wolkow, R. A. (2020). Detecting and Directing Single Molecule Binding Events on H-Si(100) with Application to Ultradense Data Storage. ACS Nano, 14(3), 2947–2955. https://doi.org/10.1021/acsnano.9b07637