skip to main content

Title: Fermi level pinning at the Ge(001) surface—A case for non-standard explanation

To explore the origin of the Fermi level pinning in germanium, we investigate the Ge(001) and Ge(001):H surfaces. The absence of relevant surface states in the case of Ge(001):H should unpin the surface Fermi level. This is not observed. For samples with donors as majority dopants, the surface Fermi level appears close to the top of the valence band regardless of the surface structure. Surprisingly, for the passivated surface, it is located below the top of the valence band allowing scanning tunneling microscopy imaging within the band gap. We argue that the well known electronic mechanism behind band bending does not apply and a more complicated scenario involving ionic degrees of freedom is therefore necessary. Experimental techniques involve four point probe electric current measurements, scanning tunneling microscopy, and spectroscopy.
Authors:
; ; ; ; ; ;  [1]
  1. Center for Nanometer-Scale Science and Advanced Materials (NANOSAM), Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, ul. St. Lojasiewicza 11, 30-348 Krakow (Poland)
Publication Date:
OSTI Identifier:
22492930
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 18; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; DEGREES OF FREEDOM; DOPED MATERIALS; ELECTRIC CURRENTS; FERMI LEVEL; GERMANIUM; ORIGIN; SCANNING TUNNELING MICROSCOPY; SPECTROSCOPY; SURFACES; VALENCE