Gallium phosphide solar cells with indium gallium phosphide quantum wells for high temperature applications

In order to increase thermal stability of solar cells for high temperature applications, wide bandgap semiconductors such as GaP are being investigated. The addition of nanostructures, such as quantum wells to the solar cell is expected to extend sub-host bandgap absorption and photocurrent generation. Increasing current generation in wide bandgap single-junction solar cells is needed to take advantage of the benefits of wide bandgap materials. In this study, GaP solar cells were grown via OMVPE with and without InGaP/GaP multiple quantum wells (MQWs). A GaP solar cell, including 5 period InGaP/GaP MQW showed a 8% increase in integrated short circuit current density (J_sc) beyond the direct band edge at 446 nm compared to a GaP solar cell without quantum wells fabricated for this study. Low temperature electroluminescence showed a peak shift from 2.16 eV to 2.12 eV due to the addition of MQWs. An additional GaP solar cell was grown with 5× InGaP/GaP MQW and a GaAs contact layer. This cell had a measured AM0 J_sc, of 2.56 mA/cm², an open circuit voltage of 1.29 V, and an AM0 efficiency of 1.83%. The normalized temperature dependence of efficiency for a GaP solar cell was shown to have a value of of 2.78 × 10^-3 °C^-1, demonstrating an increase in efficiency with temperature.