- •High quality InGaAsP material with a bandgap of 1.0 eV was grown by MBE.
- •Room-temperature wafer-bonded GaInP/GaAs/InGaAsP SCs were fabricated.
- •An efficiency of 30.3% of wafer-bonded triple-junction SCs was obtained.
- We report on the fabrication of III–V compound semiconductor multi-junction solar cells using the room-temperature wafer bonding technique. GaInP/GaAs dual-junction solar cells on GaAs substrate and InGaAsP single junction solar cell on InP substrate were separately grown by all-solid state molecular beam epitaxy (MBE). The two cells were then bonded to a triple-junction solar cell at room-temperature. A conversion efficiency of 30.3% of GaInP/GaAs/InGaAsP wafer-bonded solar cell was obtained at 1-sun condition under the AM1.5G solar simulator. The result suggests that the room-temperature wafer bonding technique and MBE technique have a great potential to improve the performance of multi-junction solar cell.