Physical Review B 85, 115404 (2012)

Fermi level pinning can determine polarity in semiconductor nanorods

Philip W. Avraam, Nicholas D. M. Hine, Paul Tangney and Peter D. Haynes

Department of Physics and Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom

First-principles calculations of polar semiconductor nanorods reveal that their dipole moments are strongly influenced by Fermi level pinning. The Fermi level for an isolated nanorod is found to coincide with a significant density of electronic surface states at the end surfaces, which are either mid-gap states or band-edge states. These states pin the Fermi level, and therefore fix the potential difference across the rod. We provide evidence that this effect can have a determining influence on the polarity of nanorods, and has consequences for the way a rod responds to changes in its surface chemistry, the scaling of its dipole moment with its size, and the dependence of polarity on its composition.

Last updated: 5 March 2012