Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 5: Photovoltaic

HL 5.8: Vortrag

Montag, 23. März 2009, 12:30–12:45, POT 151

Influence of the excess carrier density depth profile on the photoluminescence yield — •Sebastian Knabe and Gottfried H. Bauer — Institute of Physics, University of Oldenburg, Germany

The photoluminescence (PL) emitted from excited semiconductors provides access via Planck's generalizes law to parameters like splitting of quasi-Fermi-levels, optical absorption, temperature and is originated by radiative recombination. The photon flux monitored in the detector is composed of the individual fluxes emitted from each volume element of the sample isotropically into the solid angle 4 π and particularly propagating across the sample to the surface.

We numerically reproduce the spectral PL by a one-dimensional diffusion excess carrier profile for depth dependent emission, including surface recombination velocities, excess carrier lifetimes and diffusion lengths, considering as well optical absorption, reflection at surfaces and according phase accumulation by a matrix transfer approach.

As the splitting of quasi-Fermi-levels usually is deduced experimentally from the high energy wing of the spectral PL-yield we show the limits and quantify the accuracy of this methods versus different excess depth profiles resulting from various surface recombination velocities and from depth dependent carrier lifetimes as well. We furthermore discuss the difference in spectral PL-behavior between a plane wave approach applicable for layer thicknesses being small compared with the laser excitation area and small spot excitation e.g. for SNOM experiments.