Berlin 2005 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 64: Photovoltaik II

HL 64.2: Vortrag

Mittwoch, 9. März 2005, 11:00–11:15, TU P-N202

Laser doped crystalline silicon solar cells — •A. Esturo-Breton, M. Ametowobla, J.R. Köhler, and J.H. Werner — Institut für Physikalische Elektronik, Universität Stuttgart

We report on a laser doping technique that creates pn-junctions for crystalline silicon solar cells. Here, spin on coating of a phosphorous containing liquid serves as a doping precursor on 0.35 Ωcm p-type crystalline silicon wafers. A Nd:YVO4 pulsed laser scans the sample. Each pulse melts a thin silicon layer and phosphorous atoms diffuse into the molten silicon before the molten layer recrystallizes again. An increase of the laser pulse energy density increases the emitter thickness and reduces the sheet resistance of the emitter and blue response of the cell. PC1D simulations indicate that the decrease of the blue response of the cells with increasing pulse energy density is a result of the increase of the emitter thickness. Secondary Ion Mass Spectroscopy (SIMS) measurements prove that overlap between the laser pulses reduces the phosphorous concentration at the surface. The result is an increased contact resistivity between metal and semiconductor and, therefore higher series resistance of the solar cells.