Positive or negative gain: Role of thermal capture cross sections in impurity photovoltaic effect

In this work, we carried out a numerical study on the role of thermal capture cross sections in impurity photovoltaic (IPV) effect for silicon solar cells doped with indium. The short-circuit current density, the open-circuit voltage and the conversion efficiency of the IPV cell were calculated in dependence of variable electron and hole thermal capture cross sections of indium in silicon. We found that the thermal capture cross section of electron is crucial to the device performance and that of hole has few influence on the cell property for this IPV cell since acceptor-type indium impurity level is near the valence band edge. If the electron thermal capture cross section is less than 10(-20) cm(2), a positive gain of conversion efficiency for the IPV cell would be presented. We concluded that those impurities with small electron (or hole) thermal capture cross sections may be suitable for use in the IPV cell with acceptor-type (or donor-type) impurity level near the valence (or conduction) band edge. These results may help to evaluate the potential of the IPV effect for improving cell efficiency according to the thermal capture cross sections of the impurity in host semiconductor. (C) 2011 American Institute of Physics. [doi:10.1063/1.3663280]