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HL: Fachverband Halbleiterphysik
HL 17: Poster I
HL 17.28: Poster
Montag, 25. Februar 2008, 16:30–19:00, Poster D
Modelling of spectral photoluminescence yields from Cu(In1−xGax)Se2 thin film absorber — •Sebastian Knabe, Levent Gütay, and Gottfried Heinrich Bauer — Institute of Physics, Carl von Ossietzky University Oldenburg, Germany
Photoluminescence provides means to determine different physical semiconductor properties, such as spectral absorption, defect densities and their respective energy levels, and excess carrier densities which might be expressed in terms of quasi-Fermi levels. For multilayer systems glass substrate/CIGSe-absorber/CdS-window layer we have calculated the luminescence photon flux propagating towards the detector with a 1D matrix transfer formalism. Light entrance side has been chosen through the CdS-window as well as through the glass substrate; the detector is located at the CdS-window side. For excess carrier depth profile forming the basis for the luminescence by radiative recombination we introduce a carrier generation profile dependent on absorption coefficient and photon energy, and calculate carrier densities with bulk life time/diffusion length LD, and surface recombination velocities at rear Sd and front side S0 and solve the continuity equation. We analyze the influence of LD, Sd, S0 on the spectral shape of the luminescence yield including interference effects and discuss the suitability for the extraction of the splitting of quasi-Fermi levels which in solar cell absorbers quantifies the quality of the photo excited state and limits the potential open circuit of finally processed diodes.