Surface functionalization of wide-gap semiconductors

The use of semiconductor devices as biochemical sensors requires their funtionalization e.g. with proteins, which allow specific molecules or chemical processes to be monitored selectively. For stability reasons, these functionalization layers are best attached covalently. Several methods are available to chemically bind molecules to semiconductor surfaces. Depending on the initial termination of the surface by H or OH groups, one generally uses either the so-called hydrosilylation or the silanization routes. In recent years, we have systematically investigated the hydrosilylation of single-crystalline Si, amorphous hydrogenated Si, Si nanowires and Si nanocrystals.

Alkyl layers formed via hydrosilylation on Si substrates show a very good electrical insulation as well as low defect densities of at the interface. However, if charge transport is desired across the functionalization, alkyl layers on Si are less than optimal. One reason can be seen directly from the diagram: The large offset between the conduction and valence bands of Silicon and the corresponding highest occupied and lowest unoccupied molecular orbitals of the molecules in the functionalization layer (HOMO and LUMO, respectively) impedes charge transport. One way to decrease this offset is to use semiconductors such as diamond, group-III nitrides or SiC with a large band gap. We are studying different routes for the covalent attachment of alkyls on these substrates and characterize the resulting heterostructures with respect to their structural, electronic and vibrational properties, with a special emphasis on SiC.

Selected publications

  • Functionalization of 6H-SiC surfaces with organosilanes
    Applied Physics Letters 92 153301 (2008)
    S. J. Schoell, M. Hoeb, I. D. Sharp, W. Steins, M. Eickhoff, M. Stutzmann, M. S. Brandt
    Download
  • Direct biofunctionalization of semiconductors: A survey
    Feature article, physica status solidi a 203 3424 (2006)
    M. Stutzmann, J. A. Garrido, M. Eickhoff, M. S. Brandt
    Download 

Funding

TUM Technische Universität München TUM Technische Universität München Physik Department Elektrotechnik und Informationstechnik TUM Technische Universität München
 

Recent publications

Interaction of Strain and Nuclear Spins in Silicon: Quadrupolar Effects on Ionized Donors

Phys. Rev. Lett. 115, 057601 (2015)

D. Franke | F. Hrubesch | M. Künzl | H. W. Becker | K. M. Itoh | M. Stutzmann | F. Hoehne | L. Dreher | M. S. Brandt

Online Reference

see also: Nuclear Spins of Ionized Phosphorus Donors in Silicon

Phys. Rev. Lett. 108, 027602 (2012)

L. Dreher | F. Hoehne | M. Stutzmann | M. S. Brandt

Online Reference

Ultrafast electronic read-out of diamond NV centers coupled to graphene

Nature Nanotechnology 10, 135 (2015)

A. Brenneis | L. Gaudreau | M. Seifert | H. Karl | M. S. Brandt | H. Huebl | J. A. Garrido | F. H. L. Koppens | A. Holleitner

Online Reference

Bipolar polaron pair recombination in polymer/fullerene solar cells

Physical Review B 92, 245203 (2015)

A. Kupijai | K. M. Behringer | F. Schäble | N. Galfe | M. Corazza | S. A. Gevorgyan | F. C. Krebs | M. Stutzmann | M. S. Brandt

Online Reference

Broadband electrically detected magnetic resonance using adiabatic pulses

Journal of Magnetic Resonance 254, 62 (2015)

F. Hrubesch | G. Braunbeck | A. Voss | M. Stutzmann | M. S. Brandt

Online Reference

High cooperativity coupling between a phosphorus donor spin ensemble and a superconducting microwave resonator

Appl. Phys. Lett. 107, 142105 (2015)

C. W. Zollitsch | K. Mueller | D. Franke | S. T. B. Goennenwein | M. S. Brandt | R. Gross | H. Huebl

Online Reference

Submillisecond Hyperpolarization of Nuclear Spins in Silicon

Phys. Rev. Lett. 114, 117602 (2015)

F. Hoehne | L. Dreher | D. Franke | M. Stutzmann | L. S. Vlasenko | K. M. Itoh | M. S. Brandt

Online Reference