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Register a new userModelling Multi Quantum Well Solar Cell Efficiency
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Authors
James P. Connolly
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The spectral response of quantum well solar cells (QWSCs) is well understood. We describe work on QWSC dark current theory which combined with SR theory yields a system efficiency. A methodology published for single quantum well (SQW) systems is extended to MQW systems in the Al(x) Ga(1-x) As and InGa(0.53x) As(x) P systems. The materials considered are dominated by Shockley-Read-Hall (SRH) recombination. The SRH formalism expresses the dark current in terms of carrier recombination through mid-gap traps. The SRH recombination rate depends on the electron and hole densities of states (DOS) in the barriers and wells, which are well known, and of carrier non-radiative lifetimes. These material quality dependent lifetimes are extracted from analysis of suitable bulk control samples. Consistency over a range of AlGaAs controls and QWSCs is examined, and the model is applied to QWSCs in InGaAsP on InP substrates. We find that the dark currents of MQW systems require a reduction of the quasi Fermi level separation between carrier populations in the wells relative to barrier material, in line with previous studies. Consequences for QWSCs are considered suggesting a high efficiency potential.
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