Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 112: Energy materials: CIGS and related photovoltaics

HL 112.10: Vortrag

Freitag, 4. April 2014, 12:00–12:15, POT 112

Simulation of temperature dependent admittance spectra of Cu(In,Ga)(Se,S)2 solar cells and interpretation of capacitance steps — •Michael Richter¹, Christian Schubbert¹, Patrick Eraerds², Jürgen Parisi¹, Ingo Riedel¹, Thomas Dalibor², and Jörg Palm² — ¹Energy and Semiconductor Research Laboratory, Department of Physics, University of Oldenburg, Carl-von-Ossietzky-Strasse 9-11, 26129 Oldenburg, Germany — ²AVANCIS GmbH, Otto-Hahn-Ring 6, 81739 Munich, Germany

Reproducing the complex electronic device response of Cu(In,Ga)(Se,S)2 thin film solar cells by comprehensive numerical modeling is a feasible way to gain information about the device physics. Based on extensive material and device characterization we built up a simulation model that reflects not only room-temperature measurements of the current voltage and quantum efficiency but also temperature dependent admittance spectra in the temperature range from 130 K to 330 K. The individual contributions to the device admittance could be assigned to the carrier freeze out, relaxation of defects located in the bulk and in the space charge region. One dominant signature, commonly termed N1 signature, is ascribed to a second depletion region formed by a valence-band barrier at the Cu(In,Ga)(Se,S)2/Mo(Se,S)2 interface. The latter assumption is further evidenced by the correlation of the N1 signature with the roll-over behavior in temperature dependent current-voltage measurements. Furthermore, simulation of sulfur content fluctuations at the back region of the absorber shows the dependence of the roll-over on back contact properties.