Dresden 2011 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 79: Photovoltaics: Mainly Silicon

HL 79.5: Vortrag

Donnerstag, 17. März 2011, 15:30–15:45, FOE Anorg

Modulated photoluminescence studies for lifetime determination in amorphous-silicon based passivation of crystalline-silicon wafers — •Florian Effenberg, Rudolf Brüggemann, and Gottfried H. Bauer — Institute of Physics, Carl von Ossietzky University Oldenburg, Germany

Efficient passivation of interface defects is crucial in the development of efficient amorphous silicon / crystalline silicon heterojunction solar cells. Pre-treatment of the crystalline silicon wafer prior to the amorphous-silicon deposition determines the density of interface defects to a large degree. In addition, the deposition of the passivation layer itself determines the density of interface defects. By modulated photoluminescence, we study the influence of these interface defects on the recombination of excess carriers in wafers with different passivation schemes. Emphasis is laid on the deposition of amorphous-silicon passivation layers, which will also be part of the final solar cell. The analysis of modulated photoluminescence shows that the effective lifetime can be determined from the frequency response of the photoluminescence signal. For the modulated photoluminescence measurements at room-temperature we detail the excitation-density dependence of the excess-carrier lifetime and compare its variation for different passivation schemes. From the excitation-density dependence we draw conclusions on the energetic variation in the density-of-states of the interface defects and the absolute density.