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Very Low Surface Recombination Velocity of Silicon Substrates Passivated with Quinhydrone-Methanol (QHY-ME) Solution
B. Chhabra, R.L. Opila, C.B. Honsberg
Lifetime, Surface Recombination Velocity, Quinhydrone
Wafer-based Silicon Solar Cells and Materials Technology
Subtopic: Mono- and Multicrystalline Silicon Materials and Cells
Event: 24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany
Session: 2CV.2.63
1645 - 1648
ISBN: 3-936338-25-6
Paper DOI: 10.4229/24thEUPVSEC2009-2CV.2.63
0,00 EUR
Document(s): paper


The surface passivation effects of HF terminated silicon surfaces using quinhydrone-methanol and iodine-methanol are investigated. The surface recombination velocity (S) is demonstrated for various thicknesses and resistivities of silicon substrates passivated with these chemical solutions. Quinhydrone-methanol (QHY-ME) has bigger ionic radius and results in higher minority carrier lifetimes. It provides better chemical screening against oxygen and is therefore much stable in air as compared to iodine methanol passivation. QHY-ME is easy, nonhazardous, a room temperature passivation scheme, and gives repeatable results. It resulted in best minority carrier lifetime of 3.3 ms for n-type high resistivity 100 -cm Si substrate (S of 7 cm/sec) and 1.1 ms for p-type low resistivity 280 μm substrate (S of 10.2 cm/sec); both at an injection level of 1x1015 cm-3 thus proving its utility as an important characterization tool for different types, resistivity and thicknesses of silicon substrates. The lifetime is measured using the WCT-120 Sinton Lifetime Tester and surface recombination velocity extracted. The injection level dependent lifetime of these chemically passivated silicon substrates is also demonstrated for the first time in this paper in order to determine the change in surface properties with carrier density.