(Invited) Defects and Dopants in Silicon and Germanium Nanowires

Several architectures for ultra-scaled devices targeting classical and quantum information processing as well as chemical sensing rely on silicon and germanium nanowires (SiNWs, GeNWs). Despite the efforts in the preparation and characterization of these nanostructures some fundamental issues remain relatively unexplored. In particular the investigation of  defects at the interface between the semiconductor and its oxide or other semiconductors or oxides in core-shell structures represent an important challenge, as the NW diameter reduces and the surface-to-volume ratio increases [1,2]. The current experimental data and understanding of the n-type doping of silicon and germanium nanowires produced by different methods will be reviewed. The role of hydrogen and defects at the interface between the semiconductor and its oxide [3-5] in the donor de-activation mechanisms, and the effect of the confinement and dielectric mismatch in determining the donor electronic wave function will be discussed. The implications of the differences between the electronic properties of interfacial defects in silicon and germanium with their respective oxides will be also addressed.

References:

[1]   V. Schmidt, S. Senz, and U. Gösele, Appl. Phys. A. 86, 187 (2007)

[2]   M. T. Björk, H. Schmid, J. Knoch, H. Riel and W. Riess, Nature Nanotech. 4, 103 (2009)

[3]   M. Fanciulli, A. Vellei, C. Canevali et al., Nanosci. Nanotechnol. Lett. 3, 568 (2011)

[4]   M. Fanciulli, A. Molle, S. Baldovino, A. Vellei, Microelectronic Engineering 88, 1482 (2011)

[5] S. Paleari, S. Baldovino, A. Molle, and M. Fanciulli, Phys. Rev. Lett. 110, 206101 (2013)