Integrated non-III-nitride/III-nitride tandem solar cell

III-nitrides have recently been demonstrated as potential photovoltaic device material particularly in the high-energy portion of the solar spectrum [1–2]. The large lattice mismatch between InN and GaN however, makes it difficult to grow good quality high In-composition InGaN films for low bandgap subcells. The integration of III-N based solar cells, which have currently been demonstrated to work well above 2.0 eV, with mature IV and III–V based solar cell technologies, which work well at bandgaps ≤ 2.0 eV, has the potential to improve the efficiency of current multi-junction solar cells. In this paper, we present the first on-wafer integration of InGaN/GaN solar cells with non-III-nitride (GaAs) solar cells.