Charge carrier recombination in hydrogenated amorphous and microcrystalline silicon

Recombination of excess charge carriers in disordered solids is complicated, yet it is important to understand these processes in order to know what determines the electronic quality of these materials.

We investigate recombination in hydrogenated amorphous silicon, and other related silicon morphologies with pulsed electrically and optically detected magnetic resonance which gives microscopic information about the type of defects involved in the recombination. We collaborate on these questions with Klaus Lips from Helmholtz-Zentrum Berlin fur Materialien und Energie (formerly Hahn- Meitner-Institut).  P. C. Taylor from the Colorado Energy Research Institute, and A. Madan from M. V. Systems.

a-Si:H recombination sketch

Sketch of the band diagram of hydrogenated amorphous silicon. There is a wide range of defect in this disordered materials can cause recombination of excess charge carriers.

a-Si:H Rabi wiggles

Plot of the charges detected after a coherent spin excitation as a function of the excitation length and the applied magnetic field. At about 347.5mT, an oscillation is visible representing the coherent nutation of spins which control charge carrier recombination.
Our recent results on this topic:

S.-Y. Lee, S.-Y. Paik, D. R. McCamey, J. Hu, F. Zhu, A. Madan, and C. Boehme*
Spin-dependent processes in amorphous silicon-rich silicon-nitride
Appl. Phys. Lett.
97, 192104 (2010).

J. Behrends*, K. Lips and C. Boehme
Observation of precursor pair formation of recombining charge carriers
Phys. Rev. B
80, 045207 (2009).

(Editors' suggestion)

T. Herring, S.-Y. Lee, D. R. McCamey, P. C. Taylor, K. Lips, J. Hu, F. Zhu, A. Madan, and C. Boehme*

Experimental discrimination of geminate and non-geminate recombination in a-Si:H

Phys. Rev. B 79, 195205 (2009).

C. Boehme*, J. Behrends, K. v. Maydell, M. Schmidt and K. Lips,
Investigation of hopping transport in n-a-Si:H/c-Si solar cells with pulsed electrically detected magnetic resonance
J. Non-Cryst. Solids, 352, 1113 (2006).

Principal Investigator: Christoph Boehme, Department of Physics and Astronomy, University of Utah,
115 S 1400 E, Salt Lake City, UT 84112-0830, phone 801.581.6806 fax 801.581.4801,
See the University of Utah content disclaimer