Highly conductive p + + -AlGaAs/n + + -GaInP tunnel junctions for ultra-high concentrator solar cells

Tunnel junctions are key for developing multijunction solar cells (MJSC) for ultra-high concentration applications. We have developed a highly conductive, high bandgap p ( + + )-AlGaAs/n ( + + )-GaInP tunnel junction with a peak tunneling current density for as-grown and thermal annealed devices of 996 A/cm (2) and 235 A/cm (2), respectively. The J-V characteristics of the tunnel junction after thermal annealing, together with its behavior at MJSCs typical operation temperatures, indicate that this tunnel junction is a suitable candidate for ultra-high concentrator MJSC designs. The benefits of the optical transparency are also assessed for a lattice-matched GaInP/GaInAs/Ge triple junction solar cell, yielding a current density increase in the middle cell of 0.506 mA/cm (2) with respect to previous designs. Copyright (c) 2014 John Wiley & Sons, Ltd.